The grey triggerfish has a unique, recognizable shape: it has a pointed face and a laterally-compressed body, meaning it is much taller than it is wide. They have two dorsal fins, one that contains three spines and a second that looks like your more typical fish fin but moves in an undulating motion. When the fish is triggered (so to speak) by a predator, it will dart into a small crevice and fan out its spines to wedge itself in place. Triggerfish can also change colors to blend into their surroundings, making it even harder for predators to spot. They are preyed upon by larger fish, including sharks and grouper.
Grey triggerfish have small mouths but strong jaws. They use their sharp teeth to drill holes in the shells of prey like mussels and urchins. They will hover above the sand to search for prey, and sometimes will use their teeth to grab prey, turn them over, then ram forward and crush the underside of their shells.