### Identification Commonly known as a "Shag Rug" nudibranch, *Aeolidia filomenae* is a master of disguise. Growing up to 120mm, its broad, flattened body is densely carpeted in hundreds of leaf-like cerata (respiratory plumes) that give it a distinctly "shaggy" appearance. While its base color ranges from translucent grey to deep mahogany, look for the "frosted" tips—a dusting of tiny, opaque white specks concentrated on the cerata. To distinguish it from the nearly identical *A. papillosa*, look for a "bald" triangular clearing on the back just behind the rhinophores; in *filomenae*, this area is sharply defined and lacks the dense cerata found elsewhere.
### Habitat & Range This is a cold-water specialist of the Northeastern Atlantic, ranging from the British Isles and the Norwegian coast down to the Iberian Peninsula. It is a true denizen of the rocky intertidal and shallow subtidal zones. During low tide, you’ll find them tucked into moist, shaded crevices or clinging to the undersides of boulders where the humidity remains high.
### Behaviour *Aeolidia filomenae* is a slow-motion wolf of the tidepool. Primarily nocturnal or crepuscular, it emerges as the tide rises to hunt. When disturbed, it will bristle its cerata, creating a defensive "puff" of plumes to confuse predators. Its breeding is equally conspicuous: look for elegant, white, concertina-like coils of eggs—resembling ruffled lace—attached to rock faces near anemone colonies.
### Diet This species is a specialist carnivore, preying almost exclusively on sea anemones, particularly the Beadlet Anemone (*Actinia equina*). It uses a specialized radula to rasp away at the anemone’s base, often spending days slowly consuming a single large individual.
### Fascinating Fact The Shag Rug is a biological thief! When it consumes an anemone, it prevents the prey's stinging cells (nematocysts) from firing. It then transports these live "stolen weapons" through its digestive tract and stores them in specialized sacs at the tips of its own cerata. Any fish daring enough to nip at the nudibranch receives a face full of hijacked stings!