A marine mollusc has hundreds of eyes in its armour that can see images.

Credit: Alan Cressler

Christine Ortiz at the Massachusetts Institute of Technology in Cambridge and her colleagues studied the structural, optical and mechanical properties of the eyes of Acanthopleura granulata (pictured) using various experimental and computational techniques. Unlike in most animals, the microscopic lenses are not organic, but are made of the mineral aragonite. These minimize light scattering because they are made of large and aligned crystals. Projecting images through the lenses showed that they could resolve an image of a potential predator of around 20 centimetres in size from about 2 metres away.

The shells are much weaker at these points than elsewhere, but the organism has evolved ways to compensate for the structural weakness, the team found.

Science 350, 952–956 (2015)