Lion's Mane Nudibranch (Aeolidia papillosa)

Tidepool Tim says,  “Lions' mane nudibranchs are the kings of the sea slug group.  We find them in low water among the rocks and are always impressed with their size alone.  Once we put them in our aquaria - we see just how big and imposing they are! Supposedly they feed on anemones though we have never witnessed this. They have a neat mane of lobes of tissue called 'cerata'.  These nudibranchs are common throughout the world in coldwater environments. They feed on anemones like Urticaria and Metridium.”