I know there are natural formations that resemble objects, but I believe that Native Americans also worked items as an art form and the following are what I believe were created from stone for their enjoyment. I try to see if the piece has been worked in some way or a cavity has been placed or expanded.
I found this many, many moons ago north of San Rafael, California. I picked it up as a neat rock, but when I started cleaning it, the face appeared. I have tried to show in the close up the chip marks and how it has been worked. This has not been done by erosion in my opinion and possibly was
This is a small grinding platform but I think in the far right photo is a face of sorts. The two eyes on the top, a nose with nostrils, and the mouth.
I call this my " Alien", as I think it resembles what they always portray an alien looks like. The shape of the head and in the second photo, the right ear, nostril, and mouth. Every person I have shown it to in person always says the same thing, it's an alien.
This is small grinding/nutting stone but I think it resembles a frog or reptile.
This looks like a ghost in pain or howling. The right eye, a nostril, and mouth. This is a grinding piece.
Another face. The eyes are in the area that has been smoothed down, a small nostril, and the mouth. In photo three, the top has been flattened and I think the eyes were drilled or expanded when you look up close.
A grinding piece, but I think it looks like an animal head with the eyes, and the nose and mouth in the middle photo.
Small grinding/nutting stone but if look closely at eyes, they are not just natural cavities and you can see the drill marks in the left eye.
Nice grinding piece, and up close you can see the work done.
Smiling frog maybe. Two eyes and large mouth.
I see a person sitting against a tree under a limb, where you can see the head, forehead, nose, eye, and legs in a sitting position. In the second photo, there are two stick people. A friend thought this might be a Shaman's stone.
I have had these for many years and have always questioned if the black lines were not man made, and in the far right photo you can see the lines do not come through the bottom. Not sure, but interesting.
I was watching a show one night and they showed what they called a " Core" where flakes had been taken off to make tools, and it looked very much like this item and it is very clear to see where the flaking was done.
This is from a Kentucky collection and I won it on an on line auction.
Another auction item that was listed as hematite.
Nice little nutting/grinding piece, but when you are holding it in person it looks like there are two faces and one looks like it is agony like a couple of above pieces.