Crabs are animals that make an appearance in A Tale of Two Pygmies Part 1 and in part 4 of "A Quest Called Tribe" as a monster.
The crabs are either blue or red and look like a normal crab. The crab monster, on the other hand, is a red crab in yet a very large size (shown larger than the pygmies).
The crabs have made two appearances in the comics so far. Their first appearance was in A Tale of Two Pygmies Part 1. They first appeared when Nooby was swamped by the waves after being buried under Ooga's sandcastle. When the wave receded, Nooby was covered in crabs and was quickly eaten away. They also appeared in A Tale of Two Pygmies Part 2 as one of the items Nooby brings back when Ooga tells him to steal the Gem of Life.
The monster crab here located the boy tribe, Sun, and Kinsee in their hiding spot and captures them all. Its evidence of appearance are a bunch of small bubbles (in which Ooga mistakes Dooby for blowing them). This monster was killed when Troin punctures it from below and Nooby plugs the hole with a helmet, thus making it self-destruct and sending a claw flying toward a big orange bowl (where Newbie is supposedly going to pickle the captured pygmies).