A heart shaped hole, how cool! That one sounds special! I've also heard of them being called holey stones and that is where the word, holy comes from. They are supposed to bring a person good luck, especially if you find one. I've found them in parking lots where they put stones around bushes and buildings. You can look through the hole, at the moon and make a wish. Mine are mostly the size of a walnut. Some are smooth, some are sort of rough and some have more than one hole. I have one that is the length of my palm, is flat, and is half an inch thick. I found it while hiking. Sometimes tumbled gemstones have a hole. I have a malachite one and some amber ones. I put a cord on them, to wear as pendants. I wear some of my holey stones that I found outside, too. You can also hang them over a door for good luck. It must take a very long time for water to drill a hole all the way through! Nature is so patient!