Interesting character indeed It appears to be a sedimentary stone, sand stone, and the formations in it suggest gypsum or selenite have semi crystallized to make the waves. Look up desert roses Yours is rather worn but that symmetry reminds me of them.
Like ddancer says. Looks like a desert rose. Maybe it will make it to the ancient aliens show. I think there was a piece of toast that had an image of jesus on it that sold for big bucks. Perhaps you could get lucky like that. Put it on ebay for 50,000$ see what happens. You never know.