The thin, spiny structure that form the skeleton of a sponge

The spicules are the thin and spiny structure that forms the skeleton of a sponge. The spicules provide the structural support and they are small needle-like in a shape. The spicules consist of calcium carbonate and silicon dioxide. It is found in many sponges of the skeleton, they are basically like crystals and they have a pointed and hard and sharp body. Like animals, the sponges also posses some sort of skeleton which gives shapes to their body. The skeletal system of the sponge is like a needle or cluster in shape.

most community's take hundreds of years to become stable

b. read the phase at the intersection of any given temperature and pressure.