It's like convergent evolution in nature - there are only a few possible 'best' solutions, so at some point everyone uses that one. One example would be eyes i

It's like convergent evolution in nature - there are only a few possible 'best' solutions, so at some point everyone uses that one. One example would be eyes in mammals and eyes in cephalopods: they are extremely similar safe for some details (the location of the blind spot is different, but it's there) even though both groups are hundreds of million of years apart!