These are minute biconcave disc-like structures, flat in the centre and thick and rounded at the periphery. What are they?

These are minute biconcave disc-like structures, flat in the centre an

1.	These are minute biconcave disc-like structures, flat in the centre and thick and rounded at the periphery. What are they?
Answer» These are minute biconcave disc-like structures, flat in the centre and thick and rounded at the periphery. What are they?