Remember these snails? This is a Purple Sea Snail (Janthina umbilicata). I wasn't expecting to see them right now, but I found a few while doing a survey on Salmon Creek Beach tonight (25 January 2018). [Those are millimeter marks on the ruler, so the snail was ~10 mm across.]
During the 2015-2016 El Nino, many Purple Sea Snails washed ashore in Bodega Bay. I wrote a post introducing this species on 20 January 2016 — click here to review that summary (including a nice video!).
Purple Sea Snails are often associated with By-the-wind Sailors (Velella velella). Sure enough, there was a handful of Velella washed up today. Here's one:
I'd be very interested in hearing about any other Purple Sea Snail sightings. So if you see one, take a picture, and let me know!