Bamboo can grow 35 inches per day. That's about 1.46 inches (3.7 cm) per hour. I think that's a about the upper limit on the growth of a large complex organism.

There are many reasons why this is easier for a plant than an animal. Matter can be neither created nor destroyed. For an animal, food is broken down and basic nutrients are carried by the circulatory system to provide the energy and amino acids to create new proteins. An inert animal only has the resources it brought with it. In a plant photosynthesis allows a plant to use primarily water and carbon from the air surrounding it in the continuous construction of new cells.

Additionally a stalk of bamboo has really two purposes: structural and vascular. A cross section of bamboo basically has radial symmetry and looks the same no matter where you slice it. An animal's limb is made of more kinds of tissue. Muscle must be anchored to bone in some places and move freely in others. Joints require careful matching of physical features and a system of lubrication. In all case the growth of one sort of tissue out pacing another could be disastrous, so you're limited by whichever component grows the slowest. Animal growth is just very carefully orchestrated by comparison.

Finally animals have a much much higher metabolism, and that requires a much more active circulatory system. Insects lack a heart and you can see they are rather limited in size, yet trees grow to enormous size without a heart, because it's not really important that materials in their circulatory system reach their destination quickly. We also have a lot of specialized organs, while most of a plants needs are satisfied by a few different kinds of tissues that are not grown in just one vulnerable point. All of this explains why my lawn can get run over with a mower and fare much better than I would. Your trolls would have to survive trauma in the first place to be able to heal or regrow, and you will be just as hard pressed to find an explanation for their durability.

You can make your trolls a bit more feasible by making them a bit more like bamboo I guess. Their excretory system could rely more on their skin, and liver and kidney functions could be performed by tissue just under the skin throughout their body. I guess your trolls would be quite stinky. They could be made of more flexible material than bone, like cartilaginous fish. They could be cold blooded and possess a very slow metabolism. That would limit them to very sedentary lifestyles, and fast movement in only quick anaerobic bursts. With reduced metabolic needs, a reduced blood flow might be accommodated by the valves that already exist in our blood vessels and rhythmic contractions throughout the circulatory system.

Bamboo can grow 35 inches per day. That's about 1.46 inches (3.7 cm) per hour. I think that's about the upper limit on the growth of a large complex organism.

There are many reasons why this is easier for a plant than an animal. Matter can be neither created nor destroyed. For an animal, food is broken down and basic nutrients are carried by the circulatory system to provide the energy and amino acids to create new proteins. An inert animal only has the resources it brought with it. In a plant, photosynthesis allows it to use primarily water and carbon from the air surrounding it in the continuous construction of new cells.

Additionally, a stalk of bamboo has really two purposes: structural and vascular. A cross section of bamboo basically has radial symmetry and looks the same no matter where you slice it. An animal's limb is made of more kinds of tissue. Muscle must be anchored to bone in some places and move freely in others. Joints require careful matching of physical features and a system of lubrication. In all cases the growth of one sort of tissue outpacing another could be disastrous, so you're limited by whichever component grows the slowest. Animal growth is just very carefully orchestrated by comparison.

Finally, animals have a much much higher metabolism, and that requires a much more active circulatory system. Insects lack a heart and you can see they are rather limited in size, yet trees grow to enormous size without a heart, because it's not really important that materials in their circulatory system reach their destination quickly. We also have a lot of specialized organs, while most of a plant's needs are satisfied by a few different kinds of tissues that are not grown in just one vulnerable point. All of this explains why my lawn can get run over with a mower and fare much better than I would. Your trolls would have to survive trauma in the first place to be able to heal or regrow, and you will be just as hard pressed to find an explanation for their durability.

You can make your trolls a bit more feasible by making them a bit more like bamboo I guess. Their excretory system could rely more on their skin, and liver and kidney functions could be performed by tissue just under the skin throughout their body. I guess your trolls would be quite stinky. They could be made of more flexible material than bone, like cartilaginous fish. They could be cold blooded and possess a very slow metabolism. That would limit them to very sedentary lifestyles, and fast movement in only quick anaerobic bursts. With reduced metabolic needs, a reduced blood flow might be accommodated by the valves that already exist in our blood vessels and rhythmic contractions throughout the circulatory system.

Bamboo can grow 35 inches per day. That's about 1.46 inches (3.7 cm) per hour. I think that's a about the upper limit on the growth of a large complex organism.

There are many reasons why this is easier for a plant than an animal. Matter can be neither created nor destroyed. For an animal, food is broken down and basic nutrients are carried by the circulatory system to provide the energy and amino acids to create new proteins. An inert animal only has the resources it brought with it. In a plant photosynthesis allows a plant to use primarily water and carbon from the air surrounding it in the continuous construction of new cells.

Additionally a stalk of bamboo has really two purposes: structural and vascular. A cross section of bamboo basically has radial symmetry and looks the same no matter where you slice it. An animal's limb is made of more kinds of tissue. Muscle must be anchored to bone in some places and move freely in others. Joints require careful matching of physical features and a system of lubrication. In all case the growth of one sort of tissue out pacing another could be disastrous, so you're limited by whichever component grows the slowest. Animal growth is just very carefully orchestrated by comparison.

Finally animals have a much much higher metabolism, and that requires a much more active circulatory system. Insects lack a heart and you can see they are rather limited in size, yet trees grow to enormous size without a heart, because it's not really important that materials in their circulatory system reach their destination quickly. We also have a lot of specialized organs, while most of a plants needs are satisfied by a few different kinds of tissues that are not grown in just one vulnerable point. All of this explains why my lawn can get run over with a mower and fare much better than I would. Your trolls would have to survive trauma in the first place to be able to heal or regrow, and you will be just as hard pressed to find an explanation for their durability.

Bamboo can grow 35 inches per day. That's about 1.46 inches (3.7 cm) per hour. I think that's a about the upper limit on the growth of a large complex organism.

There are many reasons why this is easier for a plant than an animal. Matter can be neither created nor destroyed. For an animal, food is broken down and basic nutrients are carried by the circulatory system to provide the energy and amino acids to create new proteins. An inert animal only has the resources it brought with it. In a plant photosynthesis allows a plant to use primarily water and carbon from the air surrounding it in the continuous construction of new cells.

Additionally a stalk of bamboo has really two purposes: structural and vascular. A cross section of bamboo basically has radial symmetry and looks the same no matter where you slice it. An animal's limb is made of more kinds of tissue. Muscle must be anchored to bone in some places and move freely in others. Joints require careful matching of physical features and a system of lubrication. In all case the growth of one sort of tissue out pacing another could be disastrous, so you're limited by whichever component grows the slowest. Animal growth is just very carefully orchestrated by comparison.

Finally animals have a much much higher metabolism, and that requires a much more active circulatory system. Insects lack a heart and you can see they are rather limited in size, yet trees grow to enormous size without a heart, because it's not really important that materials in their circulatory system reach their destination quickly. We also have a lot of specialized organs, while most of a plants needs are satisfied by a few different kinds of tissues that are not grown in just one vulnerable point. All of this explains why my lawn can get run over with a mower and fare much better than I would. Your trolls would have to survive trauma in the first place to be able to heal or regrow, and you will be just as hard pressed to find an explanation for their durability.

You can make your trolls a bit more feasible by making them a bit more like bamboo I guess. Their excretory system could rely more on their skin, and liver and kidney functions could be performed by tissue just under the skin throughout their body. I guess your trolls would be quite stinky. They could be made of more flexible material than bone, like cartilaginous fish. They could be cold blooded and possess a very slow metabolism. That would limit them to very sedentary lifestyles, and fast movement in only quick anaerobic bursts. With reduced metabolic needs, a reduced blood flow might be accommodated by the valves that already exist in our blood vessels and rhythmic contractions throughout the circulatory system.