Image of Ectopleura marina (Torrey 1902)

Description:

Hydroids don't get a lot of love in the human world (nudibranchs are connoisseurs, of course), but they're often some of the most beautiful animals out there. They're also tiny, weird, and kind of hard to to ID. These aren't huge, aren't fouling, and don't have annulations below the medusae, so... Pinauay marina?