Can anyone identify what this is? It's about 1 cm long and doesn't seem to move. Found in a saltwater aquarium with material gathered from an estuary in Cornwall, UK. I'm thinking it's some kind of sea cucumber or coral as it doesn't have a head/tail or seem to move. But have no idea really… It may have been hidden under the gravel and exposed by the crab digging around, as I haven't noticed it before.
Posted by Own-Explanation2956