Isolated spicular bodies of an extinct silicious sponge. (Epistomella clivosa).
A modern sponge with silicious skeletal structure, and basal glass fibers for fixation (Holtenia…
Part of the skeletal structure of a lithisdid silicious sponge.
This illustration shows Quartz or Silica. Quarts is the most abundant mineral in the Earth's continental…
A modern Radiolarian, showing the skeletal structure of silica and the extended fleshy threads or pseudopodia.
Heliosphaera echinoides, a modern Radiolarian.
A Cretaceous sponge with silicious skeleton retaining its form. (Ventriculites simplex).