The titan triggerfish (Balistoides viridescens) is the largest triggerfish with a maximum size of 2.7ft (85cm). It lives in lagoons, passes and on the outer reef slopes in the tropical Indo-Pacific zone, where it feeds on hard invertebrates (corals, echinoderms, molluscs, crustaceans, tubeworms) and calcareous algae. Its globular eyes, positioned very high on its head, move independently and it can lock its first backbone vertically thanks to a trigger system allowing it to take refuge in the crevices without risking to be dislodged.