Protect your crab from accidental death. Hermit crabs can drown if they are not able to get out of their water bowls. Place the Natural Sea Sponge in each water dish to allow crabs a safe way in and out. Sponge may be moistened with purified water to maintain humidity level in a small enclosure. Sponges also contain nutrients such as Chitin and bits of natural shells that crabs will eat and are beneficial for their exoskeleton. Approx. 1" diameter x 1. 5".