Ninja's could tell time time by how dilated a cat's pupils were as they dilate in a regular pattern throughout the day, regardless of ambient light.
a-bucket-of-bees / reddit.com, shenhuifu.org

Ninja’s could tell time time by how dilated a cat’s pupils were as they dilate in a regular pattern throughout the day, regardless of ambient light.

Preview photo credit: a-bucket-of-bees / reddit.com
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