Chompers are essentially mutant eggs, the size of an elephant bird egg, with two beady black eyes, a horizontal "fissure" with sharp edges for a mouth, and two tube-like legs, each ending in a suction cup. They are technically omnivorous (and opportunistic), but they clearly prefer meat, hunting down and eating small animals (even larger creatures such as humans) whenever the opportunity presents itself.
Now, since monsters in my world are creatures mutated by chaos energy from the Fracture in Reality, Chompers obviously hold large amounts of chaos energy. This is why Droppers exist; regular Chompers have vestigial wings, paddle-like appendages, and every so often chaos energy causes a Chomper to develop those into actual wings and mutate a mouth on their ventral side.
Now, this makes sense; vestigial wings developing into full-blown wings isn't much of a change in the grand scheme of things, but the changes necessary for tunneling or swimming will be much more difficult, as there is no real biological basis for them. You see, in order for chaos energy to mutate something in a living thing, it has to be there.
What Chaos Energy Can Do:
Turn a vestigial trait into a fully developed trait, ie. vestigial wings into functional wings
"Awaken" dormant traits, like turning whale flippers into actual legs, complete with feet
Warp existing traits; some examples would be turning hands into hooves, talons, paws, flippers, or even wings; turning jaws into a snout; turning a nose into a trunk; or turning hide into scales.
Enhance an existing trait; ie. giving a creature supernatural strength, speed, durability, or intelligence.
Finally, chaos energy can turn body parts into tumorous growths, which develop into odd traits like additional heads, tentacles, or even parts of other organisms. This is the force behind creatures like Medusa or the chimera, which are really just ordinary creatures that have been horrifically mutated. I mention this only because it could be the only explanation for Chompers gaining tunneling appendages or fins and gills.
However, it is also extremely rare, occurring in perhaps 1% of monsters. This is my problem; in order for there to be aquatic or subterranean Chompers, they either have to start adapting for a more subterranean or aquatic lifestyle (through natural selection) before chaos energy can help them out or they have to be one of the 1% and not only mutate something that will help them dig or live underwater but survive long enough to pass that on to their offspring.
Thus, my question is How Can Chompers Develop Tunneling or Aquatic Variants?
Specifications for Best Answer:
1. Take It From The Top: The best answer will not only cover the how but why of this question, specifically why Chompers would start digging or swimming in the first place and how they'd likely adapt to do it. #1 should also apply to Chompers as Bipeds and Quads and take the abilities of Chaos Energy and how evolution works into account.
Yes, Chaos Energy mutations fall under evolutionary principles; like evolution, Chaos Energy usually adapts (AKA warps, mutates, changes) what's already there, and like evolution, there has to be an intermediary stage for something to develop (this is why the 1% has to develop tumorous growths before they can develop something like extra heads or snake hair).
2. Explain The Result: The best answer will also be thorough, covering the different ways Chompers could adapt for an aquatic/swimming or subterranean/tunneling lifestyle to determine the most likely adaptations (and path of development!) for both. I can think of two examples:
Armadillos-Like regular eggs, Chompers usually sink in water (armadillos do this too). However, they can also gulp in air, inflating their gut, then float on water (yes, armadillos do this too, they're like living submarines). Regular Chompers are vulnerable to Snapper attack, being pinned underwater or having their shell bitten through, but a floating Chomper can't be pinned and should be about impossible to bite into, since the strike of a Snapper's jaws should A) be unable to get grip or leverage and B) push the Chomper away, out of biting range. However, I'm not sure how to develop Chompers from floaters to full-blown swimmers.
Digging-Chompers have powerful acid and their jaws can eat through wooden doors, with their enamel shell (and by extension, teeth) being 1-7 times tougher than regular enamel. Thus, it seems logical that Chompers can eat their way through the ground, sort of like the dwarves in Artemis Fowl. However, Bipeds don't have a wide enough gape to fit into their own tunnels, so we either need Quad-style physiology (with a mouth at the end of the body, like Droppers or Torchblow), which can result from Chaos Energy mutations, a wider gape (just wide enough to make a hole a Biped can fit into, think thylacine gape), or scoop-like limbs and a pointed front, like a mole/bulldozer hybrid.
I'm not sure which would win out, though. The wider gape seems most likely, but after getting a wider gape, why would a Chomper develop for tunneling when it suddenly can eat everything around it with such greater ease?
As you can see, I have ideas for tunneling and aquatic Chompers. The trouble is, I don't know how they'd develop to that point.