Two HA blocks high by three long.
It's an extra for tthe Egyptian Temple mould.
The sundisc was most often used over doorways and serves the extra purpose of providing a lintel (three blocks stuck together with joints showing just makes me cringe - I've worked on building sites).
Carved from soapstone with craft knife blades, the finish is straight from the knife.
Suppose the next step is to carve a few more bits to make it worth making a mould. Obviously the open ends need pieces to close the border.
Thought I'd better post something of mine before getting shot