Answer: Invertebrates
Notes: Scientists have discovered the first fossilized tardigrades, using 3D images to study when these creatures evolved their near-indestructibility. Tardigrades, also known as water bears or moss piglets, are tiny, eight-legged invertebrates in the phylum Tardigrada. About 1,300 species are found worldwide, mostly in aquatic environments or mosses. They are extremophiles, capable of surviving extreme heat, cold, radiation, and even outer space. In harsh conditions, they enter a suspended state called "tun," where they dry out and survive for years. Tardigrades are less than 1 mm in size, with a tough cuticle and hydrostatic skeleton.
