Answer:
Chitin.
Explanation:
The structure that is not a component of wall of sponges is Chitin. Their body comprise of calcareous or siliceous spicules or protein spongin fibres. Choanocytes are the distinctive cells located in the interior body walls of sponges. Sponges are similar to other animals in many characteristics such as they are multicellular, heterotrophic, lack cell walls and produce sperm cells in order to produce offspring sexually and also different from animals due to lack of tissues and organs.
