The first scientist to describe the cell was Robert Hooke. In 1665, he examined a thin slice of cork under a microscope and observed small, box-like structures that he called "cells." Hooke's discovery was significant because it provided the first evidence that living organisms are made up of individual units called cells. However, Hooke did not realize the full importance of his discovery at the time, and it was not until several decades later that other scientists, such as Matthias Schleiden and Theodor Schwann, developed the cell theory, which established the cell as the basic unit of life.