It's too small. That's the problem that many see with the head of the Great Sphinx at Giza in Egypt: proportionately, it's much too small for the massive leonine body that it sits upon. Does this suggest that once, way back in antiquity, it originally had a different head...like that of a lion?
English geologist Colin Reader is one who thinks so, and in the video he cites another strange fact about the Sphinx's head as evidence for the theory:
We know for most of its life the Sphinx has been buried up to the shoulders and neck in sand. I've seen other places at Giza, the sand tends to protect the rocks that are buried beneath it.
The head's been exposed for almost the entire life of the Sphinx. It's been exposed to wind-blown sand, the effect of the Sun...if anything, the head should be more degraded than the body, but we see the reverse. And for me, there's only one real explanation for that. And that's that the head has been recut.
At a later stage, whatever was there originally, was retrimmed and reprofiled, to give us this pharaoh's head. The inescapable conclusion from that, is that originally this wasn't a Sphinx at all. It started life as something different.
The video goes on to cite more possible evidence for the theory, including an ancient Sphinx sculpture in the Cairo museum that also shows signs of having been recut from its original shape to give it the head of a pharaoh.
Incidentally, Colin Reader also - like fellow geologist Robert Schoch - believes that the Sphinx is older than orthodox Egyptology thinks it is - although his theory is far less radical than Schoch's, redating the famous monument only a few hundred years, rather than thousands. See Reader's journal article "Giza Before the Fourth Dynasty", or this more casual explanation of his ideas, for more detail.