What is the oldest living thing? Tell me why.

Cyanobacteria should be the oldest known life on earth, with a history of 3.5 billion years, and now it is widely distributed in the sea areas all over the world. Cyanobacteria is a kind of prokaryote. There are more than 2,000 species in the world, which are the first creatures to appear on the earth. Cyanobacteria appeared 3.3-3.5 billion years ago.

Until the Sinian 600 million years ago, multicellular organisms began to appear; 530 million years ago, Cambrian creatures exploded, and various invertebrates, mollusks, annelids and tubular plants appeared, such as trilobites.