Heliozoans, Radiolarians, Acantharians

Acantharian

Following taken from: http://tolweb.org/Acantharia/2385

"Their distinguishing features are: (1) a skeleton of strontium sulfate (SrSO4), or celestite, based on a general plan of 10 diametral or 20 radial spicules arranged in a regular pattern called Müller's law; (2) cell body covered with an outer pellicle, the periplasmic cortex; (3) the myonemes, contractile filaments grouped around the spicules."