We can fold the ears but cannot bend bones of arms. Why?

Bone is an example of a connective tissue. It forms the framework that supports the body. It also anchors the muscles and supports the main organs of the body. It is a strong and nonflexible tissue. Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds.

Another type of connective tissue, cartilage, has widely spaced cells. The solid matrix is composed of proteins and sugars. Cartilage smoothens bone surfaces at joints and is also present in the nose, ear, trachea and larynx.

Bones are the combination of hard minerals and collagen which makes them so hard that it cannot be bent without breaking. Cartilage contains condrocytes that secretes a gel like substance which combines with fibers to form a flexible matrix. Thus cartilages are flexible and can be bent easily.