That's the infamous" Ace hardware paint rock"-those were thought to be extinct...those spots are where oxygen and CO2 are exchanged enabling the rock to breathe..These were from the Phylotonicmyass Era.
Kt, I hope it's fenced in from rock rustlers....If you see them, you know what to do-

Thanks Kon, I knew I had a special rock but didn't know what kind. Yes, I know what to do...BLAM!!

Kt

This is very weird to discover that I have viewing stones too. Every bamboo I have planted seems to have at least one big stone somewhere near its base. Unfortunatey it's too cold to view the viewing stones right now without turning oneself into yet another viewing stone.