The Noble Sea Lemon gets its name both from its obvious similarity to the fruit and the fact that, when removed from the water, it smells like citrus.  At first sight it can be mistaken for the Monterey Dorid or Heath’s Dorid.  Look for a full white branchial plumage and brown markings that do not extend onto the tubercles as they do on the Monterey and the Heath’s (sometimes). The tubercles (bumps) also appear to be much more consistently rounded and they come in various shades of yellow and white.  The Noble Sea Lemon is one of the largest nudibranchs in the Salish Sea and can reach up to 10 inches or 25 cm!