Agmata is a proposed extinct phylum of small animals with a calcareous conical shell. They were originally thought to be cephalopods or annelid worms. The living animals filled up to five-sixths of th

The Cambrian is the first geological period of the Paleozoic Era and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma to the beginni