Ok.  Tiny, tiny, tiny.  Maybe 8 mm? The microscopic setting on the camera was the only saving grace when it came to documenting these little white balls of sluggy fluff.  For identification, I had to turn to the inaturalist community, and as usual they came through.  Apparently, there are numerous teensy white dorid species in the Pacific Northwest.  Luckily, this one has a noticable tail, long, tall fuzzy papallae and relatively long rhinophores for its size and family (Onchidorididae). Check out the fact sheet on Bill Rudham’s Sea Slug Forum.  There’s some pretty useful discussions there.  These particular ones were found on a piece of sargassum seaweed that was trapped in between floats on a dock.