Cyanobacteria, unusual worm like life-forms and marine organisms did not exist in precambrian time.

The statement is False.

Precambrian Time spans from about 4.6 billion years ago to about 540 million years ago. Fossils of some bacteria and cyanobacteria are an evidence that the life existed in Precambrian Time. They were the first organism that showed about 3.5 billion years ago. These unicellular organisms lived in the oceans. The first multicellular organisms evolved many years later, around 700 million years ago. Some fossils suggest the presence of some jellyfishes and worm-like forms that lived in the oceans. The land was not settled in the Precambrian time.