Spongy bone, also known as cancellous bone, is a type of bone tissue found primarily at the ends of long bones and in the interior of others, such as the pelvis and vertebrae. It has a porous, lattice-like structure that makes it lighter than compact bone while still providing strength and support. This unique design allows for the storage of bone marrow, which is essential for producing blood cells. The spaces within spongy bone are filled with red or yellow bone marrow, depending on the body's needs. Red marrow is responsible for producing red blood cells, white blood cells, and platelets, while yellow marrow mainly stores fat. The structure of spongy bone also helps to absorb shock and distribute forces during physical activities.