### Identification The Nobby Okenia (*Okenia nodosa*) is a miniature masterpiece of the reef, rarely exceeding 10mm in length. This sea slug features a translucent, milky-white body that appears almost ghostly. Its most defining field marks are the blunt, finger-like papillae (nodules) arranged in a neat row around the mantle edge, with a singular, striking row running right down the center of its back. Each of these nodules is tipped with a vibrant, "caution-light" yellow or orange. To tell it apart from the similar *Okenia pellucida*, look at the shape of the appendages: *O. nodosa* has short, rounded bumps, whereas *O. pellucida* sports much longer, spindly filaments.
### Habitat & Range This species is a wide-ranging inhabitant of the Indo-West Pacific, found everywhere from the Red Sea and South Africa to the tropical waters of Australia and Japan. It prefers shallow, subtidal rocky reefs and silty harbor environments. You won't find it crawling in the open; it is almost exclusively located on or near its specific host colonies in sheltered crevices.
### Behaviour In the field, the *Okenia nodosa* is a slow-moving, solitary creature. It spends much of its life stationary, blending into the background. Like most nudibranchs, it is a simultaneous hermaphrodite. When two individuals meet, they engage in a gentle "dance" to exchange sperm, later depositing a tiny, coiled white egg ribbon on the substrate that resembles a microscopic lace doily.
### Diet This nudibranch is a highly specialized carnivore. It feeds exclusively on ctenostome bryozoans, particularly those in the genus *Amathia*. Using a specialized, tooth-lined tongue called a radula, it rasps away at the bryozoan zooids, effectively "mowing" the colony as it moves.
### Fascinating Fact The *Okenia nodosa* is a master of "living camouflage." Its nodules don't just mimic the color of its prey; they actually replicate the physical texture of the bryozoan colonies it inhabits. It is so well-hidden that underwater photographers often only discover they’ve found one after reviewing their photos of the bryozoan itself!