Yesterday these shells were the homes of living amoeba. The slide was left on the microscope overnight and now the shells are empty, giving a view of their interiors and showing how they were made.
The shells are made artifacts, of bits of rock, dirt, minerals, quartz and even diatoms which are made of organic silica. Made artifacts? Like a tool user makes? Yes. Single celled tool users. How about that? 
Here is a video of the shells on a slide
, sort of a "Field Trip around a deserted city.
1. Difflugia Corona. They call this species "corona" because they add 3 or more little pointed bits of rock to the top of the shell, either as decoration or as a deterrant to other microbes that might want to eat them. In this one, you can clearly see the opening where the amoeba would stick out his pseudopods to pull in food or junk he wants to add to the house.
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2. A 4 image stack of another shell.
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3. A 4 image stack. Showing the points on his "crown".
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4. A 5 image stack.
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5. Another 5 image stack with a diatom shell for size comparison. This one has also added other rubble to his shell for camouflage.
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