4,540,000,000 (4.54 billion) years ago Formation of planet Earth - Usher's date was ).Archeozoic: end of Azoic to 2,500,000,000 years ago: The era of the earliest living beings on earth.The amoeba has no hard part, but some single cell organisms produce microscopic skeletons or shells. Fossil evidence is consistent with these gene-based estimates. which, from a supposed resemblance.the blossom of a liliaceous plant have been denominated Encrinites". But things changed in the : There were no land animals and extinctions were confined to water life.
Judging from the past we may safely infer that not one living species will transmit its unaltered likeness to distant futurity." (Charles Darwin) From primal swamp to speaking humans: Ernst Haeckel said (1903) that the Pithecoiden (monkey) theory of human evolution requires tracing our animal ancestors before monkeys.
"More than 3.5 billion years ago, small single-celled organisms acquired the capacity to photosynthesize" "Plants were restricted to the aquatic world until three billion years later, the first uncontroversial evidence for life is found 2,700,000,000 years ago.
The reference relates to sulphate and iron reduction as early forms of microbial respiration.
Galena can contain minor amounts of antimony, arsenic, bismuth, cadmium, copper, silver, and zinc See and stalagmites.
Encountering impermeable strata (such as toadstone) it forms underground lakes in the limestone which overflow to the surface as natural springs (a resurgence).