Wine-plume Dorid (Acanthodoris nanaimoensis)
This nudibranch was photographed on Bodega Head on 7 July 2012. Note the white/gray background color, the yellow-tipped papillae, and the red (wine-colored) rhinophores and margins of the gill plume.
Here's a view head-on where you can also see the narrow yellow margin.
The rhinophores are chemosensory organs (rhinophore means "bearing a nose"). To increase the surface area for smelling, the rhinophores often have additional folds or lamellae (see close-up below).
This species has been reported eating bryozoans and compound ascidians (tunicates). In the first photo above, there are bryozoans on the rock to the right of the nudibranch (they look a bit like lace), but I don't know if the nudibranch was eating them.
The genus, Acanthodoris, means "spiny goddess of the sea", and refers to the spiny-looking papillae covering the body surface (see below).
Keep your eyes open for this beauty when tidepooling along the rocky outer coast!