Final answer:
Endoskeletons are internal skeletons that offer support, protect organs, and aid in movement. Bones in mammals and calcium-rich plates in echinoderms are examples of endoskeletons.
Explanation:
Endoskeletons are hard, mineralized structures located within the soft tissues of organisms, providing support, protecting internal organs, and enabling movement through muscle contractions. Examples include the skeletons of humans and horses. In the context of the given question, bones in mammals and calcium-rich plates in echinoderms are both examples of endoskeletons.
Learn more about Endoskeletons in Biology here:
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