Sea slug?

[khrios]

I found what seems to be a sea slug in my nano. Will it harm anything?

 

[coralfarmer]

It is a Black Limpet (Scutus sp.) it is nocutrnal, they are opportunistic scavangers great on algae. I kept one in my fish only system for a few years. But I don't know if I would trust it in a reef tank.