an extremely rough estimate for the total number of animal individuals that have ever existed on Earth, including invertebrates and vertebrates, is approximately 4.5 x 10
(4.5 sextillion).
/
510.000.000.000.000 m2 earth surface
=
8.82353*10
animals per 1m2 ever lived
More than 100,000 individual animals can live on one square meter underground, alive now