Mesohyl - thin middle layer that is analogous to connective tissue in higher animals. It is characterized by a jelly-like matrix with collagen, spicules, and various cells embedded within. Cells called archaeocytes found in the mesohyl are amebocytes (cells capable of movement) that can transform into other sponge cell types. These cells aid in digestion, nutrient transport, and are even capable of developing into sex cells. Other cells called sclerocytes produce skeletal elements called spicules that provide structural support.