 pile on: A petrified flower? Not so much. Although this is called a chrysanthemum stone, there’s no real plant matter involved. Well, not in the way you think, that is. During the Permian age (248 to 290 million years ago), a thick layer of mud containing all sorts of silt and organic marine material lay at the bottom of the ocean. Calcium carbonate and strontium sulphate precipitated within that mud and was compressed as more layers of muddy ooze piled on top. Over time, this sedimentary rock hardened, leaving these crystalline “flowers” trapped inside a dark rock, such as limestone or dolomite. Who knew something so beautiful could come from something so muddy? Photo cred: cobalt123 via Flickr