In 1665, Hooke used a primitive microscope to examine a thin slice of cork. He observed small, box-like compartments that reminded him of the cells in a monastery. He named these compartments "cells" because of this resemblance.

However, it's important to note that Hooke was actually observing the dead cell walls of the cork, not living cells.

Later, Anton van Leeuwenhoek, using more powerful microscopes, observed living cells like bacteria and red blood cells.