Phyllidia varicosa Lamarck, 1801
This very common tropical Indo-Pacific species ranges from southern and eastern Africa, throughout the Indian, and east and central Pacific Oceans. Its eastern range extremes are Hawaii in the north and the Society Islands in the southern hemisphere.
Large adult specimens can range between 90-115 mm in total length. Characteristic of this species are the light blue ridges, capped with rows of brilliant yellow tubercles. The depressed regions between the ridges are black. The rhinophores, nestled at the anterior base of two longitudinal ridges, are also bright yellow.
This species produces a defensive toxic mucus with a delightfully strong, pungent odor. It has been reported to kill lobsters, shrimp and poecilid fish when introduced into the same aquarium!