If so, you have a palmaris longus tendon. It is as useless and ugly as you are, but luckily can also be easily ignored and discarded. It is maintained, but not loved - just quietly resented by its surrounds.
I have it...
You're so mean
If it makes you feel any better, I too am holding back human progress with my useless tendon.
My arms don't go straight out kid...nice try.
Sorry, didn't mean to be ableist. Perhaps try having a loved one slice open your arm?
The joke's on you, I'm double jointed at the elbows.