Found all around the world, including off the coast of Australia, the tripod fish can live in depths of up to 6 km below the surface. The purpose of those super-long fins is to elevate the tripod fish to about a metre above the seabed, where the ocean's current is strong. This means that small prawns and crabs are ushered right into the tripod fish's gaping mouth, and all it has to do is stand there.