In the open ocean, there’s nowhere to hide, but the lookdown fish – a name it probably gets from the steep profile of its head, with mouth set low and large eyes high – is a master of camouflage. Recent research suggests that it uses special platelets in its skin cells to reflect polarised light (light moving in a single plane), making itself almost invisible to predators and potential prey. The platelets scatter polarised light depending on the angle of the sun and the fish, doing a better job than simply reflecting it like a mirror.