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This article is about Rockgrub in Below Zero. Click here for information on this subject in Subnautica.

The Rockgrub is a passive fauna species. Despite superficially resembling an invertebrate, the PDA states that it is a possible relative of the Sand Shark.


The Rockgrub is tiny in size. Its body is slim, round and segmented. It also has two swimming fins on either side and a larger flipper serving as the tail. The creature has five appendages on each side of its body, and a circular maw containing many small teeth.

The Rockgrub's most notable feature is the constant, bright bioluminescent green glow that its entire body emits to light up a small spherical area around itself.


The Rockgrub swims rather quickly within its vicinity, seemingly scavenging whatever it could find. They are most visible in darker areas such as caves. Rockgrubs tend to traverse on tunnel walls or any surface in its vicinity.

Rockgrubs can be picked up, it used as bait for Rock Punchers to which they are prey.

Data Bank Entry


A small, luminescent scavenger, roughly thumb-sized. This creature may be a distant relative of the sand shark, sharing that species' unusual limbs, segmented exoskeleton and burrowing behavior.

1. Jaw:
Its circular set of teeth is designed to tear up clumps of coral and sea grass caught on the rocks.

2. Limbs:
Five legs, two arms and a large flipper allow the rockgrub to cling to and walk across rock faces in search of food, and swiftly swim to safety when under attack.

3. Green Luminescence:
Glowing green in the dark would seem like a poor survival strategy, but this adaptation may be a mating behavior or other specialized process, engaged in by only a fraction of the total population at any one time. Or perhaps being eaten is simply part of the rockgrub's lifecycle.

Assessment: Harmless

Source: Scan Rockgrubs