Are you familiar with this animal? The species name is "leonina," referring to a "lion" and the mane-like appearance of its oral hood and the peripheral tentacles.
Here's the entire animal viewed from below:
You can see that the oral hood is very large relative to the rest of the body. Also visible is a long slender foot, and rounded, leaf-like cerata extending out to either side of the foot.
This is Melibe leonina, sometimes called the Lion Nudibranch or Hooded Nudibranch.
This nudibranch has some very unusual features. Along with the impressive oral hood used to capture prey (such as small crustaceans), look for the interesting rhinophoral processes (flap-like or ear-like) and the small, grooved rhinophores at their tips — see images below.
Melibe inhabits kelp forests (especially Giant Kelp, Macrocystis pyrifera) and eelgrass beds (Zostera marina). They are occasionally found in Bodega Harbor.
We were somewhat surprised to find two small Melibe in a Bull Kelp (Nereocystis luetkeana) holdfast washed up on Salmon Creek Beach on 13 August 2014.
Here's a picture of the Bull Kelp holdfast. I photographed it because there was also a small Five-ribbed Kelp (Costaria costata) attached to it, and I still have yet to find Five-ribbed Kelp growing on Bodega Head.
When we looked closely at the holdfast, Eric noticed an unusual brown blob. This is what Melibe looked like on the holdfast, out of the water. It's just below the tip of Eric's forceps:
It makes sense, but it made me smile to see this description from a paper written in 1923:
"The body-substance of Melibe leonina appears as a mass of brown jelly, when the animal is alive or freshly caught..."
Kudos to Eric for realizing this bit of "brown jelly" in the holdfast was worth looking at. Who knew it would turn out to be a lion!
P.S. The quote above is from Agersborgh, H.P. . 1923. The morphology of the nudibranchiate mollusk Melibe (syn. Chioraera) leonina (Gould). Q. J. Microsc. Sci. 67: 507-592.