At first glance, this Virgin Mary Image on A Stone Carved by Nature, Found on the Beach does bear a resemblance to the Virgin Mary, but look more closely - in particular at the area the vendor thinks is her arm:
Three years ago I was walking along a beach in Michigan, enjoying the beautiful sunny day wrought by God's handiwork. I stepped on a stone and bent down to rub my foot when I noticed this stone was very polished and smooth. When I picked up the stone I was stunned to see that the image of our Virgin Mother was staring at me! I have kept this stone with me, showing it to friends and relatives. The image is on a raised stone upon stone. Someone noted that it may be a fossil on top of the stone. The difference with this Mary is that she appears to have a hand over her eyes, as she herself cannot face the horrors of humankind. As I hold it, I feel such a sense of security and serenity. It has been my treasure and I am now offering it to pass along the solace it has given me.
Now, if that's an arm, then the BVM has two elbows. I see two possibilities - one is that she suffered from elephantosis, the other being that it isn't the Virgin after all, but some pagan goddess, and that's a whopping great dildo she's got there!