The second two are the bristles of a polychaete worm. I had posted a couple similar to these back in 2007, but these were done with the DIC dialed up to "unreal color". Normally I don't do that, but on second glance I sort of like them!
All were with the Olympus BHS. Darkfield for 1st image, DIC for the others. Objectives used (top to bottom ) were 4X, 20X, 40X and 100X (S Plan Apos).



