Eyes don’t even have to be organic. While most animal lenses are made of proteins, the fuzzy chiton – an armoured relative of snails and other molluscs – has lenses made of rock. The lenses are made of aragonite, a type of limestone and the same stuff that the chiton’s shell is made of. These rocky eyes give the chiton a view that’s a thousand times fuzzier than ours, but that’s still good enough to see passing predators. The eyes also erode as the chiton ages, which might explain why it has more than a hundred of them.
Read more: Chitons see with eyes made of rock