I have 3 various pieces that I am interested in getting more information about. My boyfriend and I found them in the forest by a closed down elementary school. They are not magnetic and they are all dark brown in color with similar shaping. Upon lifting them, they seem heavier than their size and they all feel quite dense. They dimple inward, as if a Sasquatch depressed their fingers and or large thumbs in it if it was made of clay. The 3 pieces seem to have broken off from each other over time as evidenced by fitting together like a 3D puzzle. On the back side of the pieces, you will see disturbed/jagged impact lines of some sort. Please advise, accordingly. Thank you for your time in advance.

Piece 1: 10 cm X 15 cmPiece 2: 8 cm X 9 cmPiece 3: 5 cm X 6 cm