A microscopic tardigrade going for a stroll through some algae.

A microscopic tardigrade going for a stroll through some algae.

Tardigrades (/ˈtɑːrdɪɡreɪdz/) known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals.[2][6] They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär ('little water bear').In 1777, the Italian biologist Lazzaro Spallanzani named them Tardigrada (/tɑːrˈdɪɡrədə/), which means "slow steppers"

Tardigrades are near-microscopic animals that can survive some of the most extreme conditions on Earth, including freezing temperatures, crushing pressures, and even the vacuum of space

Tardigrades, often called water bears or moss piglets, are near-microscopic aquatic animals with plump, segmented bodies and flattened heads. They have eight legs, each tipped with four to eight claws or digits, and somewhat resemble the hookah-smoking caterpillar from "Alice in Wonderland." Though tardigrades are disarmingly cute, they are also nearly indestructible and can even survive in outer space

https://www.livescience.com/57985-tardigrade-facts.html

The largest adults may reach a body length of 1.5 mm (0.059 in), the smallest below 0.1 mm (0.0039 in). Newly hatched tardigrades may be smaller than 0.05 mm (0.0020 in). For comparison, grass pollen is typically 0.025–0.04 mm (0.00098–0.00157 in).