Silicoflagellate, Distephanus crux
This is from the diatomaeous earth used in formulating a spray-on textured ceiling. It was
found in the course of examining the ceiling material for the presence of asbestos.
Transmitted Off Crossed Polarized Light Illumination
Silicoflagellates are amoung the group of life forms that make up the phytoplankton. Their cast (seen here) is an opaline
silica and they are often encountered in diatomaeous earth deposits. Silicoflagellates tend to be marine, autotrophic
flagellates producing their own food through photosynthesis. Many of the species are very sensitive to temperature and so
become important indicators of paleoclimates in fossil deposits.
Significance in the Environment:
Silicoflagellates are often found in diatomaous earth deposits and aid in the characterization of the conditions under which
the deposit formed. Near the ocean they are found in surface deposits as a result of ocean spray
Silicoflagellates are characterized by a basal ring with extending spines. Some species have elaborate domes extending from
one surface of the basal ring, which results in a hemispherical asymmetry. They are typically 20 to 50 micrometers in
diameter but some may be as large at 100 micrometers. The structure is isotropic silica and so is dark
between crossed polarizing filters. The Distephanus genus has a apical (central) window.
Haq, Bilal U. and Anne Boersma, INTRODUCTION TO MARINE MICROPALEONTOLOGY, Elsevier, pp. 267-273, 1978 (ISBN 0-444-00267-7)