Help ID'ing black snail? Friend or Foe?

[Vaughn]

Caught the little critter underneath a coral frag, any idea what he is?

 

[FreshSaltH2o]

Pics in the water with white light would be beneficial almost looks like black stomatella or black ab size? Any other features?

 

[Soren]

Elephant slug/snail? I don't know much about them, but I've come across them in my information searches.