But, now it is also known, that one sperm cannot, repeat cannot,
break through the outside barrier on the egg by itself. It has to have the
help of thousands and thousands of other sperm also attaching the outside of the egg, so that one lucky sperm can finally penetrate the corona radiata (the outside barrier of the egg) to fertilize the egg.
There was a photograph published several years ago, which showed all of these sperm trying to burrow their way into an egg.