Subclass Placoperla Cavalier-Smith, 2012 Diagnosis: imbricate cercozoa that secrete a test of mineralized spherical perles or siliciﬁed plate scales that are typically double tiered with a perforate upper tier. Includes superorders Perlatia and Placoﬁla. Order Perlofilida Cavalier-Smith, 2012 Diagnosis: near spherical heterotrophic and phagotrophic non-flagellate protists with uniformly extremely thin but stiff, symmetrically radiating, unbranched filopodia (unlike Cristidiscoidea), lacking a microtubule axoneme and lacking extrusomes; unlike in Cristidiscoidea, cell surface covered with one or more layers of spherical siliceous perles bounded by a wall with numerous uniformly sized but irregular-shaped small holes. Centrosomes and interphase microtubules absent, unlike Heliozoa; mitochondrial cristae flat; numerous Golgi dictyosomes closely surround the eccentric nucleus; thin ectoplasm without a dense layer underlying the plasma membrane, unlike Apusozoa; microbodies associated with lipid drops and mitochondria.
Pinaciophora fluviatilis, pores visible – fountain of the Royal Palace het Loo, the Netherlands