Vince, when I saw "Philippines" in your post title, I had the feeling that by clicking on it, it would be someone going after big treasures, or Yamashita's lore, or symbols and signs and caves, etc..... And sure enough, I was right.
The Philippines is chalked FULL of lore and superstition. Treasures are said to be hither and yonder in varieties of caves, ruins, etc.... All you need is a detector that goes 6 to 9 meters deep, and it's most-certainly there. Naturally cryptrograms, symbols, codes, markers, secret maps passed down through the ages that need to be deciphered, etc... are all part of the lore.
Your heart-shaped rock is just a coincidence and random shapes meaning nothing. You are reading way to much into ghost stories, sorry to say.