1. As long as the endoskeleton of the heterostracans remains unknown there must always be doubt about the pattern.

2. Endoskeleton : Skeleton lying inside body. Made up of bones and cartilages.

3. Length frequency analysis, rostral length, endoskeleton length and statolith are used in determination of the age and growth in cephalopod.

4. Skeleton: they possess an endoskeleton of cartilage, or bone. The characteristic notochord is replaced by intersegmental vertebrae in vertebrates.

5. Austrian Death Machine. I Am A Cybernetic Organism Living Tissue Over Metal Endoskeleton.

6. Bones are rigid organs that form part of the endoskeleton of vertebrates.