Ten Commandments

These larger than actual size prop tablets were used in church today for the sermon.

In recent centuries the tablets have been popularly described and depicted as round-topped rectangles but this has little basis in religious tradition.

According to rabbinic tradition, they were rectangles, with sharp corners, and indeed they are so depicted in the 3rd century paintings at the Dura-Europos Synagogue and in Christian art throughout the 1st millennium, drawing on Jewish traditions of iconography.

The length and width of each of the Tablets was six Tefachim, and each was three Tefachim thick; roughly a 50 cm square (20 in) that was 25 cm thick (10 in), though they tend to be shown larger in art. Also according to tradition, the words were not engraved on the surface, but rather were bored fully through the stone.

The rounded tablets appear in the Middle Ages, following in size and shape contemporary hinged writing tablets for taking notes (with a stylus on a layer of wax on the insides).

wikipedia: Tablets of Stone