That's an Eastern Pacific black ghostshark, native to the coast of southern California. It's one of 94 new species the California Academy of Sciences documented in 2009. Ghostsharks (or chimaeras) are, unsurprisingly, related to sharks, but only distantly. Their evolutionary path branched away from their better-known cousins some 400 million years ago. What makes them different? Among other things, retractable sexual appendages on the foreheads of the males.
California Academy of Sciences: New Species of "Ghostshark" Named By Academy Researchers
Treehugger: 94 New Species Described by the California Academy of Sciences in 2009