Which cells produce calcareous and siliceous spicules in animal sponges?

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In animal sponges, the production of skeletal material is carried out by specialized cells known as sclerocytes (or scleroblasts). These cells are classified based on the chemical composition of the spicules they generate:

Calcoblasts: These cells are responsible for secreting calcareous spicules, which are composed primarily of calcium carbonate.1
Silicoblasts: These cells produce siliceous (glasslike) spicules, which are made essentially of silicic acid.1

These sclerocytes are found within the mesohyl of the sponge and are believed to be derived from archaeocytes.1