Alright, so this is another creature-design question. It's been a while since I've posted one of these, so this is overdue in my opinion.
Engulfers are large (think car or van-sized) caterpillar-like creatures with large mouths (and lungs, they can breath air, and they have cartiliginous skeletons). Put more specifically, their bodies are blubbery and barrel-shaped, their face is convex (shaped like the inside of a bowl) and has a fang-lined slit for a mouth. Usually, this mouth is wide open, revealing a remarkable resemblance to a cave and a long, thick tongue.
You may wonder if they have eyes; the answer is that they have four (sort of). One pair of eyes goes above the mouth and appears to be simple spots above the mouth, and the other, the false eyes, is a pair of thick stalks on top of the head, each of which ends in what appears to be a giant, bloodshot human eye. These are used to lure in prey, to distract attacking creatures, and to pummel struggling prey into submission.
Supporting this rotund body is a series of blob-like legs; these are prolegs and push or rather bounce against the ground to drive the creature forward. That's right; this giant hungry caterpillar is going to bounce toward you (bum-BUM-bum-BUM-BUM-bum), its tongue wriggling toward you, its eyestalks flailing. As if that wasn't enough, their body ends in a roughly cylindrical club.
I say "roughly" because the club tapers to a point and has ridges of rather large spikes along its length. It's sort of like a Stegosaurus thagomizer and very much like a Rolling Pin of Death, if that helps you visualize This club is connected to a thick tail, which is flexible enough to swing forward and strike opponents in front of it's face, and is about the size of a beanbag.
Finally, Engulfers have bulbous segments, like caterpillars, all over their barrel-shaped bodies and their thick, rubbery hide and blubber layers makes most attacks either bounce off, slip off, or fail to penetrate. These creatures are, quite obviously, caterpillars mutated by magic, but I want some logical pretext for these things, otherwise they might break my reader's SOD (Suspension of Disbelief).
So my question is: How Plausible Is This Creature? Additionally, if it isn't plausible, please include how it could be made plausible.
Finally, I appreciate your input and feedback. If you choose to close- or down-vote, please give me an explanation so I can improve this question and make better ones in the future. Thanks everyone!