Halgerda dorid, Halgerda sp.
This is Halgerda batangas. If you're not a slug geek, this might not be a very helpful description. Yes, this is a slug. More specifically, it's type of a dorid nudibranch. The black tree-like structure at left is the animal's gill plume. The two cylindrical projections at the right are sense organs called rinophores. "Wewak and Madang", Papua New Guinea August 19, 2005