Crab Feces is a coprolyte-like resource in Subnautica 2 that doubles as high-density bioreactor fuel. It comes from a single source in the Shallows, and only one creature in the region produces it: the Coral Crab.
Where Coral Crabs spawn
Coral Crabs are large, passive crustaceans that hide inside Coral Domes in the Shallows biome. They surface when you approach, but they will not attack. Several Coral Dome sites exist across the starting region, with the most accessible one sitting northeast of the Lifepod near the Welcome Center landmark.
A second reliable cluster sits east of the Lifepod, roughly 300 meters out near the edge of the volcanic region. That area is also used as a Salt farming route, so you can collect Crab Feces and Salt deposits on the same trip.
How to collect Crab Feces
Step 1: Leave the Lifepod and head northeast toward the Welcome Center. Keep close to the seafloor so you can spot the large Coral structures.
Step 2: At the Welcome Center, take the left-hand path until the terrain opens into a flat area dominated by a giant Coral. Approach the Coral Dome to draw the Coral Crab out.
Step 3: Look around the base of the dome for small, oval-shaped deposits resting on the sand. Pick them up by hand. No tool is required, and the crab will not interfere.
Step 4: Move on to neighboring Coral Domes to gather more. Deposits respawn over time, so you can revisit the same sites once your stockpile runs low.
What Crab Feces is used for
| Property | Detail |
|---|---|
| Type | Material |
| Source | Coral Crab habitats in the Shallows |
| Stack size | 1 |
| Description | Coprolyte-like deposit of excreta with extreme energy density |
| Primary use | Crafting Biofuel Blocks at the Processor |
| Recipe cost | 2 Crab Feces per Biofuel Block |
The deposit feeds directly into the Bioreactor as fuel, and processing two of them at a Processor yields a Biofuel Block. That output is one of the most efficient power sources for a base early on, which makes the Shallows trip worth repeating whenever your Bioreactor stockpile drops.
Confirming it worked
You will know the pickup registered when the deposit disappears from the seafloor and Crab Feces appears in your inventory under Materials. At the Processor, the Biofuel Block recipe becomes available the moment two units are in storage. If the recipe stays locked, you are likely short on the required count or have not unlocked the Biofuel Block blueprint yet through scanning.