It's Geometry Monday!

Diod you ever think of looking for geometry in the Moo Goo Gai Pan? Look at that perfect pentagon. Now the question, what vegetable is that? I had thought it was a slice of water chestnut because it seemed to be sliced the same thickness--but no. And since it was on my husband's plate, I did not snatch it up to test myself. That would be rude, right? I only made him wait while I photographed it.