<Tr> <Td> </Td> <Td> <P> Placozoa </P> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Porifera (sponges): Calcarea </P> </Td> </Tr> <P> Porifera (sponges): Calcarea </P> <Tr> <Td> </Td> <Td> <P> Porifera: Hexactinellida & Demospongiae </P> </Td> </Tr>

When did the first life appear in the ways of history