Collodictyon lives in the sludge of a small lake called Ås, 30 kilometres south of Oslo.
It has four flagella - tail-like propellers it uses to move around, and can only be seen with a microscope. It is 30 to 50 micrometers long.
Like plants, fungi, algae and animals, including humans, Collodictyon are members of the eukaryote family that possess cell nuclei enclosed by membranes, unlike bacteria.
Not social creatures
Using the characteristics of Collodictyon, scientists can now infer what prehistoric eukaryotes looked like, says Tabrizi - probably a single-cell organism with finger-like structures that it used to catch microscopic prey.
"They are not sociable creatures," says co-researcher Professor Dag Klaveness, who bred millions of the tiny organisms for the study.
"They flourish best alone. Once they have eaten the food, cannibalism is the order of the day."
They have not been found anywhere but in Lake Ås.
"It is quite fascinating that we can still find these kinds of organisms after so many years," says Tabrizi.