It resembles a large crab. It has two large claws and six legs. On the top of its head, it has four small horns and in the center is one large spike. It has only one eyeball, and its iris appears to be the gemstone. Because it's only seen through Ronaldo's night vision camera, the actual color is unknown, but in the palette we see, it appears to be a dark teal color. It could be orange and white, just like its minions. It has two small pincers at its front, which is its mouth.
- Creature Creation: The crab gem monster can create smaller crab monsters, one of which pinched Ronaldo before the main monster was introduced.
- The crab gem monster resembles Gohma from the Zelda series, particularly in how it seems to use its claws to help protect its eye, which is its weak spot, and its ability to spawn smaller versions of itself.
- The Crab Gem Monster is similar to the Centipeetle Mother and the Gem Cave Creature by being able to summon smaller versions of itself.
- Like the Centipeetle Mother, its gemstone is located in the iris.
- The smaller crabs are red, which implies the large crab might be as well.