Several organisms are plentiful on earth. When speaking of "creatures" the group known as insects is the largest group of tangible creatures.
Unicellular- organisms include bacteria, the most numerous organisms on Earth. Multicellular- organisms are composed of many sells and they lie
Bacteria & Insects.
I assume you meant single "celled" organism. It is an organism (life form) that consists of only a sigle cell as opposed to most all other lifeforms on earth which are comprised of many (billions) of cells.
Pizza
fish
single celled
single-cell
Phytoplankton.
planet
Bacteria are generally considered the most numerous organisms on Earth. They are found in virtually every environment and play crucial roles in ecosystems, from aiding in nutrient recycling to influencing human health.
Fish hold the title for the most numerous vertebrates on Earth. With over 30,000 known species, they are found in a wide range of aquatic environments worldwide.
fish, birds and ants