Diatoms - Jewels of the Sea

Diatoms are unicellular algae that are found wherever there is water and sufficient light to stimulate photosynthesis. The cells may be free floating (planktonic) or attached to a substratum (sessile). The diatom cell possesses the property of being able to surround itself with a more or less rigid box-like (like a covered petri dish) skeleton of hydrated silica called a frustule. The classification of diatoms is largely based on frustule form and sculpture. Diatoms range greatly in size from 5 – 2000 μm in length, although most species encountered are in the size range 20 – 200μm. 

Traveling back to the Jurassic period!

Antique sample of a Pterodactyl Rib under a Motic B1 upright microscope

Pterodactlys were winged reptiles who lived in the Jurassic period about 150 million years ago. The specimen is a portion of a transverse section of rib (approx. 1.8mm wide) and was taken from the slate mine area of Stonesfield (Oxford, England) and has been prepared as a thin section and dated June 1855. Pterosaur bones are difficult to cut and polish to a thin section without losing material. It is a testament to the preparer that the paleohistology details are clearly visible.