The new species that came out of a São Paulo tap

Fishkeeping is a solitary hobby that requires a lot of work — perhaps as much as caring for a dog or cat, but with few affectionate interactions in return. Fans of the hobby, often known as aquarists, say it is an exercise of patience and selflessness. A photographer with a passion for nature, Fernando Barletta dreamed of becoming a biologist and found fishkeeping to be a way to get close to nature, even though he lives in the center of São Paulo, the largest city in South America. 

According to him, taking care of fish in an artificial environment is a good way to contemplate nature and meditate on life.

But in 2014, during a normal day of maintaining his 200-liter aquarium, he noticed a very small “foam” that he had never seen before. Instead of removing it or throwing chemicals to solve the problem, he did what he always had done: he observed.

The strange object was less than 25 millimeters in diameter and was translucent, whitish, and relatively flat. In time, he realized it was breathing. It was an animal. A very strange one.

He reported the discovery on an internet forum, which reached Ulisses Pinheiro, a researcher at the Federal University of Pernambuco who specializes in...