Sea Lemons (Peltodoris nobilis) are a type of nudibranch, or sea slug. They breathe through the rosette of gills sticking up from their lower back.
In nature, bright colors often mean “I taste bad…don’t eat me!” Predators have been observed spitting Sea Lemons out after getting a taste of their funky flavor.
Sea Lemons and other nudibranchs mostly feed on sea sponges.
Not only do Sea Lemons look like lemons, they smell like them too! They can grow up to almost 8 inches in length, which is big for a nudibranch.
Images: Eva Funderburgh and Vlad Karpinsky on Flickr. Sources: Wikipedia, Monterey Bay Aquarium