Our crack team of researchers here at I.N.N.I. have recently made a startling discovery. While pondering these:
We immediately thought of these:

Is it possible that these mysterious stones are actually the petrified remains of giant rabbits? Large rabbits that may be extraterrestrial in origin? For a rabbit to leave nuggets of that size, it would have to be huge as shown by the following artists rendering:
While more complete research is needed, the similarities are both frightening and striking. Perhaps Central America was once overrun with giant alien rabbits, terrorizing the inhabitants of the region with their giant fluffy tails and uncommonly large feet. We theorize that these stones spheres were really tributes to their fellow beings that had been squashed by these marauding creatures.

We will never know for sure, but the thought of monstrous extraterrestrial rabbits keeps us up at night. It also leads us to wonder if, in fact, the Jackalope is a far larger threat then we ever thought.
We say, beware of the hare. Our research continues....