In "On the Origin of Species," Darwin posited that "during these vast, yet quite unknown, periods of time, the world swarmed with living creatures".
The Precambrian seas did indeed "swarm with living creatures" and there had been evolution for tens or hundreds of millions of years before the Cambrian explosion.
He stated his concerns in The Origin of Species: Consequently, if my theory be true, it is indisputable that before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown periods of time, the world swarmed with living creatures.
Botanical compositions, swarming with nature's less appreciated creatures and extinct or mutant forms feature aquatic or tree-sized dandelions.
With starting points around the city and no fixed route, it was impossible to tell how many people actually participated, but the city certainly felt like it was swarming with a surprising number of exotic creatures.
Trapped in a clockwork castle by an unknown enemy and with no means of escape, the Doctor was confronted by the Veil, a limping and disfigured creature shrouded by a sheet and swarming with flies.
Marketplaces swarming with innocent civilians?
Markets swarming with people.
The streets were swarming with newcomers.
Paris, as always, is swarming with Americans, and these days it's also swarming with hamburgers.
