Zacharias Janssen is credited with inventing the compound microscope around 1590. While this invention wasn't directly a contribution to biology, it was a crucial stepping stone.

Here's why:

* The microscope allowed scientists to see things invisible to the naked eye. This opened up a whole new world of microscopic organisms and structures, revolutionizing our understanding of biology.

* Early microscopes were used to study insects, plants, and even blood. This led to groundbreaking discoveries about the structure and function of living things.

Therefore, while Zacharias Janssen didn't directly contribute to biology himself, his invention of the microscope set the stage for countless biological discoveries that followed.