The Rock Puncher has a bulky, armoured body. It has six articulated feet and two arms at the front. The head shows four, orange eyes at the front and and a pair of mandibles directly underneath. Its body ends in a small, short, shrimp-like tail.
Attached to the arms are two large club-like extremities, presumably used to deliver powerful strikes against hard objects.
The Rock Puncher's underside is gray with a green shade while its back is yellow with red patterns. Its arms and legs also share the similar patterns, with their tips being dark brown in color.
The Rock Puncher seems fairly indifferent to the player's presence, continuing to walk along the seafloor without paying much attention to them.
The Rock Puncher is heavily inspired by crustaceans of the order Stomatopoda, the mantis shrimps. Some members of the group possess club-like claws that are used to deliver extremely powerful blows to their prey. The Rock Puncher is essentially a scaled up mantis shrimp.
Data Bank Entry
A large crustacean which feeds on tiny larvae excavated from coral and rock with its powerful punching arms.
- The Rock Puncher's design is most likely based on the mantis shrimp.
- Early animations for the Rock Puncher can be found here.
- Gamefiles refer to the Rockgrub as "Rock Puncher Larva" but an early Trello card refers to them as "RockPuncher Food". 
- ↑ https://trello.com/c/ebmQyziR/407-rockpuncher-food-anims Dated August 16, 2014.