A Petoskey stone may look like an ordinary piece of gray limestone until you get it wet. Then a tightly packed pattern of hexagons and starbursts appears across the rock’s surface, each one representing an animal that lived during the Middle Devonian, roughly 393 to 382 million years ago. Source: Read the original article on […]
A Petoskey stone may look like an ordinary piece of gray limestone until you get it wet. Then a tightly packed pattern of hexagons and starbursts appears across the rock’s surface, each one representing an animal that lived during the Middle Devonian, roughly 393 to 382 million years ago.
Source: Read the original article on science.howstuffworks.com
