Description of Arthracanthida

Acantharea in which the bases of the spicules are pyramidal with 4-6 facets with or without basal extensions forming a more or less interlinked system. Endoplasm with numerous nuclei, pigments, inclusions and symbiotic Haptophyta. Thick capsular wall. Ectoplasm separated from endoplasm by a periplasmic cortex. Myonemes cylindrical, generally numerous. A few axopodia emerge between the spicules. Unlike the other Orders of Acantharia, gametogenesis occurs in a gamont which keeps the appearance of the trophont. The whole endoplasm is converted