Heliozoa, commonly known as sun-animalcules, are microbial
eukaryotes (
protists) with stiff arms (axopodia) radiating from their spherical bodies, which are responsible for their common name. The axopodia are microtubule-supported projections from the
amoeboid cell body, and are variously used for capturing food, sensation, movement, and attachment. They are similar to
Radiolaria, but they are distinguished from them by lacking central capsules and other complex skeletal elements, although some produce simple scales and spines. They may be found in both
freshwater and
marine environments.