A few years later, Dutch businessman Anton van Leeuwenhoek was the first to see living cells through his microscopes. Around 1674, he looked at drops of lake water, scrapings from teeth, and water from rain gutters. Leeuwenhoek was surprised to find a variety of one-celled organisms. He noted that many of them whirled, hopped, or shot through the water.

What do you think the one-celled organisms that van Leeuwenhoek found in lake water were?