Detail of radiating forked siliceous spines of Acanthocystis turfacea (Carter,1863) which have detached from the periplast under the pressure of the coverglass. A. turfacea is a centroheliozoon with tangentially layered siliceous scales and two types of forked radial siliceous spines, one short, the other long (both seen here). The radiating axopodia contain extrusomes (not seen in this image). Endosymbiotic zoochlorellae are visible in this image. From standing fresh water near Boise, Idaho.DIC.