A desmid is a single-celled algae
And then there were two! Watch this mesmerizing time lapse video of a desmid dividing. Desmids are single celled, microscopic algae that are beautifully symmetrical. Each cell has two half-cells connected in the middle by the cell nucleus.
Did you know? Desmids thrive in clear, nutrient-poor and unpolluted fresh water. They are considered an “indicator species” of water quality because they disappear when water turns murky.
Credit Dr. Jeremy Pickett-Heaps
madame scientist's not-so-mad musings 
It looked okay to begin with but then things got interesting really fast!
That seems like cheating on your radial symmetry
David Archer yes, each daughter cell is only doing half the work!
Rajini Rao And if I’ve got this right, half of each one of these critters is ancient.
Hold on, no – but some specimens would have ancient halves.
David Archer I think your second comment is right. Beginning with one cell, after multiple divisions, one of them is the oldest in the chain. You can see it in drawings of dividing desmids where the newer semicell is still small and the next division happens before it is fully grown. Does it make sense?
Rajini Rao Sure. And the odds that primordial halves have survived for any great length of time is probably not great. Who knows?
Since the name desmid comes from greek for “chain”, I’m guessing that the cells at the very ends will be the most ancient.
Wow! Thanks.
Rajini Rao
That’s beautiful! How close are Desmids to Diatoms? Do they play a role in the carbon cycle? Can we farm them to mitigate climate change?