Uni
From Burden's Landing
Sea urchin, or more specifically, sea urchin gonads.
Best place to get them is Santa Barbara Fish Market.
The shell is actually pretty delicate (hence the spikes). You can open them pretty easily by sticking two spoons in the mouth and by prying the shell open.
See Also
History
Bought and prepped live ones for the first time from Santa Barbara Fish Market on December 30, 2013.