Originally posted by renorenal:
[b]NEW
MYSTERY
I once was useful
But now, I am functionless
Blame it on evolution
Animals still have it
I am still present in the spine
And cause nothing but only severe pain
That is only when you decided
To hit me hard...
What am I? 
[/b]
It used to be a tail. 
Actual here and there a child is born which has a short tail, it
usually gets amputated. Such cases are rare.
