From the Micro Images Blog:
Chalk Dust (2500 X)
For the longest time, I wanted to see what chalk dust looked like up close. It turns out, you dont see all that much more, even at 2500x the dust is pretty fine. It is interesting to see that chalk dust is made up of two general sizes of particles, and that they tend to clump together a bit.
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Stoma (1500 X)
This is one of millions of holes found on the common leaf used for gas exchange in plants. What you see here is a waxy outer layer of leaf. Inside the hole you can also see the remains of two guard cells which help open and close this tiny pore to regulate air and water exchange. This leaf was found dried out already, which means this level of preservation is shocking. I did not expect to find anything so detailed left.
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Cobweb (450 X)
Ever wonder what that very fine cobweb looks like closer up? Well no longer. I wonder if some spiders make more curly webs than others? In the upper left corner, you have a thread of some fiber which shows just how thin the cobwebs are.
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More here.