strange invert

[homestar]

so i was cleaning out the bottom of my old reeftank that had crashed a few months ago, when i lifted out a shell from a clam i saw what looked like a centaped. it's legs were redish with a brown body, before i could get my camera it buried back under the sand. is this something that i need to remove from that tank or is it beneficial?

 

[LeslieH]

Sounds like a polychaete and probably harmless.