Look carefully at the surface now.
I'm seeing faces again! I also see raised letters of some type.
Remember this is extremely old and the images are faint.
Study the circled areas. Step back from the monitor and take your time.
Do you see the remains of a hand?
Amazing slab of some sort, don't you think? The image on the left edge of the photo looks almost south-american in nature. Was this mankinds home at one time?