While it's tough to pinpoint the absolute first recorded biological observation under a microscope, Robert Hooke is often credited with being the first to publish detailed microscopic observations.

Here's why:

* 1665: Hooke published his book "Micrographia," which contained meticulously drawn images of various objects viewed through his microscope. He coined the term "cell" after observing the honeycomb-like structure of cork.

* Prior to Hooke: While earlier microscopes existed, their resolution was limited, and their use was primarily for examining small objects rather than biological specimens.

However, it's important to note that:

* Others were experimenting: Antoni van Leeuwenhoek, a Dutch draper, was also making remarkable microscopic discoveries around the same time as Hooke. He observed bacteria, protozoa, and even red blood cells, although his findings weren't published as extensively as Hooke's.

* Earlier observations: It's possible that individuals before Hooke and Leeuwenhoek made microscopic observations but didn't record them or didn't have the technology to create detailed images.

Therefore, while Hooke is often considered the "first" due to his published work, the early history of microscopy is a complex and fascinating story involving many individuals and contributions.