What's this?

[SDP222]

My brother just setup his 30 gallon and he's 300 miles from me. He bought a piece of live rock from petco and it was in it. Is it beneficial or nusceance? In 15 years in the hobby I've never had one in mine, but I also have never bought live rock from a chain store. Any help is appreciated!

 

[Calappidae]

Stomatella Snail, Good guys that make up part of your natural CuC.

 

[SDP222]

Stomatella Snail, Good guys that make up part of your natural CuC.

Thanks, I told him it was something like that or a sea slug.