Fleas

Fleas are successful acrobats.

An excerpt from the article 15 facts about fleas
The first mention of a flea circus dates back to 1578, and a watchmaker Mark Scaliot, who created a miniature golden chain with a lock, that could be pulled by a flea. However, throughout the next two hundred years, fleas were a background for skilled craftsmen. In the 19th century, in 1812 to be precise, Goldsmith Johann Heinrich Deggeller performed with his flea circus. Since then, fleas became popular acrobats, and the idea of a flea circus conquered the entertainment industry. A flea trainer would wrap a golden harness around the flea’s neck, and attach it to various objects, such as carriages. Sometimes, fleas were glued to props, and the circus heated, so the flea would try to escape, and its movement would look like it played an instrument.

Nowadays, it is not as common and popular as it used to be, most living acrobats were swapped with mechanical, electrical, and magnetic devices.