I DON'T THINK THESE 500 MILLION SPERMS PRODUCED A DAY FUSES AND FERTILISES. WHAT HAPPENS TO THE THE REST OF SPERMS PRODUCED, WHICH DOES NOT FERTILIZE?
Millions of sperms are released by the male during one ejaculation. It takes only one out of the millions of sperms released to fertilize the single matured egg and rest of the sperm cells die in the vagina of female. The sperm cells survive only for 2-3 three days in the vagina.