The organisms were found on a whim, when a scientist decided to collect a sample of dirt during a hike in Canada. After the dirt was collected and taken back to the lab, the sample was soaked in water, which revives microbes that have gone dormant. Over the next few weeks, she checked on the dish through a microscope to see what might be swimming around, only to discover a new branch of life.
Two species of the microscopic organisms were found, called hemimastigotes. They are so different from all other living things on Earth that they don’t fit into any kingdom used to classify known organisms. It is very different form any other animal, insect or fungus, for example.
A genetic analysis shows they represent a completely new part of the tree of life. You’d have to go back about 500 million years before the first animals arose and a common ancestor of hemimastigotes could be found.