Sea Slug Hitchhiker?

[Kobin]

Hi I was wondering if this was a scutus/elephant slug. Looks like a black snail/slug and has a hard shell that's black kinda like a stomatella. It's also grazing on the algae it seems. Are these guys reef safe? Thank you

 

[Lovemyreef2015]

I would say it's a stomatella snail.