The Micrasterias apiculata is a nice desmid with a special surface -
lots of stings are covering it.

A selection from above:

(Zeiss Standard 18; Ultracondenser; Planapo 40/0.95; widefield 0.8x; S-Kpl 10x/20; MC63; 4x5" film)
Finally a division:

(like above, but Planapo 25/0.65; Kpl 6.3x/18; 6x9 cm film)
Btw, I still like the large format slides very much. :-)
Your comments are welcome.
Best wishes
Jens