<P> The earliest known life forms on Earth are putative fossilized microorganisms found in hydrothermal vent precipitates . The earliest time that life forms first appeared on Earth is unknown . They may have lived earlier than 3.77 billion years ago, possibly as early as 4.28 billion years ago, not long after the oceans formed 4.41 billion years ago, and not long after the formation of the Earth 4.54 billion years ago . </P> <P> A life form, or lifeform, is an entity or being that is living . Earth remains the only place in the universe known to harbor life forms . </P>

The first life forms to appear on earth were