Radiolarian
Radiolaire
Unicellular marine protozoan with an elaborate siliceous skeleton, living as zooplankton in open water. Their tests accumulate on ocean floors to form radiolarites. Known since the Cambrian, radiolarians are important biostratigraphic fossils.
Paleontology
Igneous rock
Roche magmatique
Rock formed by the cooling and solidification of magma, either deep underground (plutonic rock, e.g., granite) or at the surface (volcanic rock, e.g., basalt). Contrasted with sedimentary and metamorphic rocks.
Geology