opisthobranch?

I think I figured out that this is an opisthobranch rather than a nudibranch, which I learned about from another post. I don't see any gills or rhinophores. Am I on the right track? Sorry for the grainy photo.

Yes, not a nudi, but related.

Chelidonura sp

Nice close up Zippsy. It's common in the IP. Chelidonura amoena.

Thanks much for the information. I should have also mentioned that this was found at 11m at "the dropoff", Pulau Sapi, near Kota Kinabalu in the Tunku Abdul Rahman Marine Park.

I'll have to look more closely for these guys without naked gills or rhinophores. I've never noticed them before!