It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Chitons first appeared on Earth more than 500 million years ago. But according to the fossil record, the oldest chitons with eyes didn't emerge until the last 25 million years, making their eyes among the most recent to evolve in animals.
A tiny sea mollusk uses eyes made of a calcium carbonate crystal to spot predators lurking above, researchers say of the first such rocky lenses found in the animal kingdom.