Food molecules are triangular in shape and the billions and billions of them that form the make up of a sandwich all tessellate very nicely within the confines of a triangular sandwich. However being cut into a square shape causes a disturbance in ions that bind the sandwich molecules together. This results in a chemical reaction that speeds the decay of the sandwich and hence a reduction in flavour.

This phenomenon is called the St. Clair Effect after the nutritional scientist Raleigh St. Clair who first discovered this curious anomaly.

Tis true!