Where is the needle-like parts in found in sponges?

The needle-like parts in sponges, known as spicules, are found throughout their body structure. These spicules can be made of silica or calcium carbonate and provide structural support and defense against predators. They are often embedded in the sponge's mesohyl, the gelatinous matrix between the outer cell layer and the inner canal system. Spicules vary in shape and size depending on the sponge species.