GEOLOGY

Detailed explanation-1: -The oldest fossil evidence of multicellular animals, or metazoans, are burrows that suggest smooth, wormlike creatures live 900 mya or more. Found in rocks in China, Canada, India, and elsewhere, the imprints of these soft-bodied creatures reveal little else besides their basic shapes.

Detailed explanation-2: -Around 600 million years ago, the first multicellular organisms appeared on Earth: simple sponges.

Detailed explanation-3: -Appearance of animals. Animals first appeared in the Ediacaran Period (about 635 million to 541 million years ago), soft-bodied forms that left traces of their bodies in shallow-water sediments.

Detailed explanation-4: -Previously, the oldest known fossils of hard-bodied animals were from two reef-dwelling organisms that lived around 550 million years ago. Researchers have identified controversial fossils of soft-bodied animals that date to the latter part of the Ediacaran period between 577 and 542 million years ago.