1. (i) Presence of canal system and (ii) Skeleton of spicules

    (i) Presence of canal system and
    (ii) Skeleton of spicules

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  2. Skeleton of sponges is made of spicules or spongin fibres. Spicules are formed of calcium carbonate and silica.

    Skeleton of sponges is made of spicules or spongin fibres. Spicules are formed of calcium carbonate and silica.

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