I would like to have giant sand worms similar to the ones in the 'Dune' novel. What should the planet be like so that they are realistic? Giant sand worms are roughly 100m long and 5 meters in diameter. They can burrow/ dig through sand similar to earth worms, they don't need to create permanent tunnels, their tunnels can collapse after them. Their diet consists of some tiny critter in the sand, so they digest the sand and filter out the critters, similar to how whales filter tiny krill out of the water.
On earth a creature like that can't exist because sand would just crush them and digging through harder materials takes way to much energy (there was a question about that here recently). So let's change the planet to make them realistic. I don't care about whether this species could have evolved, it is sufficient that they can exist as is. The planet doesn't need to be suitable for humans but that would be a bonus.
Some parameters that could be changed:
- Lower gravity should help a lot because sand becomes less heavy but I can't put numbers on it.
- The atmosphere can be denser or thinner, atmosphere composition and temperature can be adjusted but I don't know whether that would change anything.
- The sand: Sand grains on mars are about 1000 times smaller than on earth (by diameter), even gravel with a diameter of 10cm on average could still be sand. Not sure what works best for digging.
- Shape of the sand grains: polished round almost spherical for low friction or complicated shapes for lower density?
- Chemical composition of the sand: sand is usually some silicate but if nitrogen snow at -210°C is the only way to go then so be it.
- Whatever else needs to be changed to make giant sand worms.