I found a rock like this as a child (but cream colored, fairly flat, about the size of a dinner plate, and an inch or two thick), though I'd never heard of the

I found a rock like this as a child (but cream colored, fairly flat, about the size of a dinner plate, and an inch or two thick), though I'd never heard of the phenomena from any other source until now. I think I found it on a trip, but I'm not certain which. It's probably still sitting in my parent's garden, somewhere.