You're likely thinking of Zacharias Janssen and Hans Lippershey, who were both Dutch spectacle makers credited with the invention of the compound microscope.

While they didn't directly contribute to cell theory itself, their invention of the compound microscope was absolutely crucial for its development. Here's why:

* Magnification: The compound microscope allowed for much higher magnification than previous single-lens microscopes, enabling scientists to see objects that were previously invisible.

* Observing Cells: This increased magnification allowed Robert Hooke, in 1665, to observe the cellular structure of cork for the first time. This was a pivotal moment in understanding the basic building blocks of life.

So, although Zacharias Janssen and Hans Lippershey didn't formulate the cell theory, their invention of the compound microscope was a necessary precursor to the groundbreaking observations that led to the development of this fundamental theory in biology.