Transmitted Oblique Illumination
Silicoflagellates are amoung the group of life forms that make up the phytoplankton.
Their cast (seen here) is an opaline silica and is often encountered in diatomaeous earth
deposits. This form of Silicoflagelagellate with the sharp projecting points is more
common of marine species than of freshwater species. Diatomaeous Earth is use in filters
as insulation in fire-safe file cabinets, and as a common bulking agent in construction