Small Slug-like creatures in my hermit crab's shell

[Chortanator]

Purchased some zoas, watchman goby, RBTA, and a pair of clowns from my LFS yesterday. Today noticed some black slug-like creatures poking in and out of the hermit crab's shell. There are at least 3 in the one shell, I don't see them anywhere else.

 

[vetteguy53081]

Looks like a dendrodoris Nigra slug. These are generally found under rocks during the day or crawling in the open at night. It occurs at moderately protected to moderately exposed rocky sites or shell and mat be eaten by a xanthid crab. They are harmless and will starve if no adequate supply of food is available.

 

[KJ]

Look like this.

dendrodoris nigra - Google Search

www.google.com