Jeremy,
Did you realize that you actually shot two of them? Maybe getting ready to mate 
For being so common, I think spanish shawls are one of the most beautiful nudibranchs out there.
As for critique, the "fringes" (I forget the proper term now) seem a little overexposed/out of focus and I think there is too much shadowing on the right. It looks like you used a single strobe coming from the left. If this was the case, the strobe placed right over the lens may have prevented some of the shadows. It seems that your DOF extended from the body of the more forward nudi into the 2nd one in the rear hiding in the shadows.
I really like the detail you captured in the body and the rhinophores of the slug. Nice texture. The colors are also very nice. I also like the diagonal composition.
I imagine the forward shawl saying "hey baby..." 
Are you still diving in So. Cal ?
Beautiful picture,
John