What is the shape of red blood cells?

The shape of red blood cells:

1. Red blood cells or erythrocyte is one of the cellular components of blood.
2. It is made up of millions of red blood cells.
3. This gives blood its distinctive hue and transports oxygen from the lungs to the tissues.
4. The adult human red blood cell is tiny, spherical, and biconcave, with a dumbbell form.