Why are thick and strong bones not very heavy?

Thick and strong bones are not very heavy primarily due to their unique structural composition. Bones are made of a combination of mineralized tissue and a lightweight collagen matrix, which provides strength without excessive weight. Additionally, the internal structure of bones includes a network of hollows and cavities, like the trabecular (spongy) bone, which reduces overall mass while maintaining structural integrity. This design allows bones to support the body's weight effectively without being overly heavy.