Identify the invertebrates described in each number.
1. They are soft-bodied flatworms.
2. They have no backbon, instead, they are composed of spiny speckles which serve as skeleton.
3. They are soft-bodied animals with hard external shell.
4. They have hard outer exoskeleton or cuticle and jointed body and limbs.
5. They are equipped with spiny skins and peculiar tube feet.