Ill give you a clue, the answer is in the question.
a starfish is missing a few body parts like fins and tails
A starfish is a ectotherm. (ectotherm means cold blooded)
They can regenerate body parts
A starfish has radial symmetry
starfish have bumps and spines on their body
The body cavity in a starfish contains the circulatory system and the haemal system. The body cavity also helps starfish by distributing oxygen that has been distributed throughout the body, through the body.
The Pentagon Starfish has a bump texture. The body is thick and looks like a pentagon pincushion, and tube feet cover the bottom.
Starfish have suction-like cups helps to open clams
scales but soft ones like something a seagul eats
They have special suckers on their body which cling to the rocks like suction cups.
Since the starfish is a cold-blooded animal, its body temperature is the same temperature as the surrounding water it lives in. Each starfish's temperature varies.
For a body plan, a starfish has 5-part radial symmetry, spiny skin, internal skeleton, water vascular system, and suction cup-like structures called tube feet.