Are these Faces a Prehistoric Shrine?

Bulgarian archaeologists are calling these human faces, discovered by photographer Miroslav Shobanov, a shrine dating to between 3500 and 3000 BCE.

What do you think? They certainly look like faces, but so do lots of natural rocks.

On the other hand these niches, found nearby, look definitely human-made to me. Pottery was also found nearby, and given that this is a pretty inaccessible spot, maybe it is an ancient shrine.

And while we're on the subject of Bulgarian archaeology, here is a very definite petroglyph, an Orpheus Lyre likely carved by Iron Age Thracians.