Stomatal peels

Well yes - you may well be wondering what one is. But here is a picture of one taken down a microscope and showing the breathing bits of a plant.

Its actually an impression of the plant surface, a bit like a mould taken from it, but in fine enough detail to see the cell layers. Its done in acetate, and seems to work quite well if you get the pressure your right.

So there, now you know. That's a stoma, that the plant was using to breathe with - until it got covered in acetate and other chemicals.