C is for "holy crap, this rock formation looks like Cookie Monster!"
An unusual looking rock was found in Brazil, and when it was cracked open, it looked exactly like Cookie Monster from Sesame Street! And now, it could score someone $10,000!! (See the opening of the rock below)
According to CNet.com, the owner of the rock said:
This is very unusual. There are a few famous agates out there: the owl, the scared face... there are many approximate ones but rare to find clear well defined like that. Prices can be very high. I was proposed over $10,000 by five different buyers.