Rhynia gwynnevaughanii,
Rhynia gwynnevaughanii, transverse section of a stem with diameter 1.3 mm. Rhynie (Scotland). Lower Devonian (408 million year).

I recently read an article in National Geographic about the discovery of 50 Million Year Old fossilized worm sperm.   I’ve seen other items about cells that have been individually fossilized.   I simply found the idea incredulous.  I questioned if minerals and rocks really could preserve that level of detail.   Today I decided to google a bit and see what kind of stuff was being claimed as found.

There are a number of fossilized plant stems which have been cross sectioned.   The one here in this is just one example.   Rhynia gwynnevaughanii and it pretty well lays to rest any questions one might have.   The cellular structure is so clearly visible it is amazing.  It looks like those initial slides you look at when you get your first microscope