Diatoms are tiny single celled algae (green plants) which live in little glass bottles, that is they have a cell wall made of silica. They are objects of particular beauty and quite challenging to produce a good image of, so they have long been a favourite subject of microscopists, especially those interested in optics. I chose this for my profile picture. It is a dark ground image and should appear on your screen at about 1000X magnification: the original will be about 1/10th or 1/20th mm long and barely visible to the naked eye. they are found in all sorts of scummy water, fresh or marine.
