This weird armored mollusk is called a chiton, and scientists are amazed by it. They discovered eye-like structures on its body decades ago, but they had no idea what they were made of, if they could see or just sense light, or even if they were eyes at all, because they were structurally very different from everything we’ve encountered so far.

But as it turns out, its eyes (which are used to spot predators lurking aroud) are made of a calcium carbonate crystal, a substance that commonly makes the shells of other creatures such as snails, or the rocks of caves.

“Turns out they can see objects, though probably not well,” said study researcher Daniel Speiser, who recently became a postdoctoral fellow at the University of California, Santa Barbara.

In comparison to human vision, the chiton vision is about 1000 times weaker but hey – their eyes are made out of rock ! Another interesting fact is that although chitons have bee around for 500 million years, the oldest ones with eyes appeared 25 million years, which is relatively recent, and makes them among the latest animals which developed eyes.

Researchers believed they developed this kind of eyes to see and protect against predators, and they evolved in a way that allows them to see both above and underwater.

Enjoyed this article? Join 40,000+ subscribers to the ZME Science newsletter. Subscribe now!