GENERAL HISTOLOGY

Detailed explanation-1: -This revealed that starfish ossicles are composed of single crystals of macroporous magnesium‐rich calcite (stereom), similar to the mineralised skeletal elements of echinoids and some ophiuroids (Raz et al.

Detailed explanation-2: -The ossicles are composed of high magnesium calcite, a polymorph of calcium carbonate, commonly organized into a porous microstructure called stereom [12].

Detailed explanation-3: -Starfish are layered with an upper skin made out of calcium carbonate. This strong material makes the skin tough and difficult for hunters to breakdown. Some species of starfish will even go a step further with the addition of numerous spines on their skin, acting as a layer of armour to deter predators.

Detailed explanation-4: -The lateral canals are contained within bony elements called ambulacral ossicles (11) that form an ambulacral ridge in each arm (seen as ambulacral grooves on the oral surface of each arm). Starfish also have a well developed internal skeleton made up of bony elements called dermal ossicles (12).