Intertidal, Gobernadora Island, Gulf of Montijo, Panama, 47.8mm.
The « Thorn Tooth Latirus » is a remarkable fasciolariid characterised by a long protruding 'tooth' in the anterior part of the outer lip. Such 'tooth' are more commonly seen in muricids such as Acanthina monodon (Pallas, 1774) to pry open shells of armoured prey, but is unusual among fasciolariids. O. pseudodon is also an predatory gastropod considered to feed on shelled animals including barnacles, bivalves, and vermetid worm snails; its muricid-like 'tooth' is thus thought to be a result of convergent evolution. It ranges from Mexico to Peru including Galapagos Islands, and lives among rocks of intertidal waters down to very shallow littoral waters of around -5m. It has a rather thick, dark brown periostracum when alive and much of the attractive dark/light banding pattern is concealed under it. The length of 'tooth' may vary considerably between individuals of a similar size. A common species, its typical shell length is around 50mm., while very large specimens may reach 75mm.