Gastropod mollusc. The scientific name alone sounds gross. But then, every so often, you may come across one of these mud-brown creatures as it slinks along your driveway or backyard patio—leaving behind a trail of mucous.

Take a closer look at the slug’s features: its rippled skin glistens from a mucous coating; its two antennae-like eye stalks pump in different directions, along with two lower tentacles it uses for smelling.

Certainly, slugs are likely one of the last creatures you would spend time admiring for the way they look. But it may surprise you to know that some slugs are considered the most beautiful creatures on the planet! But you will not find these kinds of slugs in your backyard.

Gracing the ocean floor are a type of sea slug called the nudibranch (NEW-dih-bronk), and they are particularly photogenic because of their variety of brilliant colors and shapes. (Nudibranch means “naked gills” in Latin and Greek because they live fully exposed without shells.)

These sea slugs come in over 3,000 species, with the smallest only a quarter of an inch long and the largest measuring a foot long. They also come in a variety of forms, with some that could be mistaken for plants or even something that is not living. The Hopkin’s rose, for instance, resembles a red-colored pom-pom used in cheerleading.

Most nudibranch live in tropical, shallow water, and spend their lives grazing the floor eating coral, sponges, fish eggs, algae, barnacles and even other nudibranch slugs.

Like terrestrial slugs, nudibranch have tentacles on top of their heads that they use to sense sight and taste. Unlike other land slugs, however, nudibranch obtain their vibrant colors through their diet!

The marine slugs absorb pigments from their prey and thus take on different colors. This allows them to blend in with the colorful sponges or corals they are feeding on, providing camouflage.

In addition to colors, nudibranch slugs consume foul-tasting poisons and secrete them through their skin, allowing them to keep predators including small fish away. For example, some nudibranch can eat the “stinging” cells of jellyfish and incorporate them in the tips of their horn-shaped cerata, giving them the ability to sting whatever comes into contact with them.

The saying “you are what you eat” has never been truer than in the case of these eye-catching creatures!