Help ID. slug?

[Anwar]

I just bought some live rock and found this dark black creature with a white dot at the tip of the antenna. Is it reef safe?

 

[rssjsb]

Could be a scutus.

 

[SushiGirl]

Looks like a little too smooth for a scutus, but who knows. My first thought was a nudibranch. What's it eating, a sponge?

They have a ton of black scutus at one of the stores here.

black scutus

Just found this Dendrodoris nigra

 

[LeslieH]

Sushi Girl's right - Dendrodoris nigra. It's a sponge eating nudibranch that occasionally shows up in aquariums.
http://www.seaslugforum.net/showall/dendnigr