Phyllidia ocellata, photographed in the waters off Pelorus Island, Queensland.
Nudibranchs (including Phyllidia ocellata) form a “clade” (meaning that all species of nudibranch descend from a common ancestor that no non-nudibranch descends from) of predatory sea slugs. Nudibranchs tend to be vibrantly coloured, and there is a great deal of variation between species in not only the colour patterns but even in the anatomy – which makes them great photography subjects!
Moth Eyes 