The Baby Flak Crab is a Hardmode critter found within the Sulphurous Sea biome after the Aquatic Scourge has been defeated. Similarly to its adult counterpart, it disguises itself as a geyser. If the player gets too close to one, it will reveal itself and run away until they are far enough from the player. Baby Flak Crabs can be caught with a Bug Net or Golden Bug Net, and will rarely drop the Geyser Shell when captured.
- The Baby Flak Crab along with the pet version are both inspired by a submission for a sulphurous sea design contest that was held on the Calamity art server. The original sprite, made by TheBlackHand#2549, was based on a more garbage wastes-like vision of the sulphurous sea.