Prasinophyte: Tasmanaceae. Light micrograph of a specimen about 90 microns in diameter. Alabama, Oligocene. Courtesy of L. E. Edwards, U.S.G.S.

Prasinophyte: Tasmanites, a long-ranging genus that may be the cyst (=phycoma) stage of a prasinophycean green alga. The circular outline of the vesicle and honeycomb-like surface pattern can be seen in this light micrograph of a stained specimen. Specimen is about 100 microns in diameter. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.