The answer to yesterday's mystery image was: The head of a paper match.
Not much time for commentary today.
Cactus (species unknown)
A cross section showing the needles as they grew. 60x.
A clump of needles at 60x.
Needles fluoresce at 60x. (Thanks for the spelling correction, Hitmouse.)
The filament from inside a clear glass lightbulb at 60x and 200x.
What is today's 200x mystery pic? Guess in the comments.