Sea Lemon nudibranch in a sandy tidepool on the Washington coast.

A sea lemon is a nudibranch, which is a sea slug with exposed gills. The gills can be seen on the back of the slug, where they appear frilly. The to "antennae" are rhinophores, which are chemosensory structures.

Taken on my trusty Pentax Optio WG-1 Digtial Camera.