Took these quotes from another place. Not my words, but something to check out.
It's a nudibranch, and as far as I know, it should feed on sponges. It must have ridden in on something more recently than 5 years ago..? Most nudibranchs have short lifespans, and I'd be very surprised if this species is an exception. I'll be interested to hear what Leslie thinks about it. The most common black nudibranch is Dendrodoris nigra, and Dendrodoris fumata can look almost just like it. The little white specks on yours, the rhinophores, and the bump in the middle remind me of Hallaxa indecora, although it should be brown rather than black. The gill looks to be positioned more like the Dendrodoris species.
http://www.seaslugforum.net/factsheet.cfm?base=dendnigr
http://www.seaslugforum.net/display.cfm?id=10413
Cheers,
Don
It certainly could be either D. nigra or fumata. One way to tell is by looking at the gills - if there are about 5 large bushy ones in a circle then it's D. fumata; D. nigra has about 10 small ones in an U or incomplete circle. Otherwise both species shows the same variation in color. They are thought to eat small sponges which hide in crevices or on the underside of rocks. It's quite likely it was hiding on the frags you bought last month.
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Cheers, Leslie
So many worms, so little time...
Natural History Museum of Los Angeles County
