Answer:
Hey!
Your answer is Pelagibacter Ubique !
Step-by-step explanation:
This organism might not sound any familiar to most people but this type of BACTERIA, dominates the oceans on Earth and form up to 1/3 of all single-celled organisms!
But the most common MAMMAL on Earth are shared between: Squirrel, Bats, Rats and Mice... *their current population is unknown but definitely much more than Humans as they reproduce at rapid rates!*
HOPE THIS HELPS!!