its a 50's bass, what is the black thing near the fretboard?
It's just an anchor for your hand to play off of. Sometimes they're above the strings, some times they're below.
My rig:

Ibanez Jetking 2 (electric)
Hohner HW300-G TBK (acoustic)

Peavey Encore 65
Crate CP-150 and building my own cabinet in the summer

Boss DS-1 Distortion
Boss CH-1 Super Chorus
Dunlop Cry-Baby Wah
They're rests for thumb slappers (rests on the lower side) and rests for the finger pickers (rests on the upper side) or at least that's what I think.

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When the electric bass was first invented, people played with their thumbs instead of their two fingers. They put their fingers on the rest.
^ Exactly it.

If you ever try playing with your thumb, you'll notice you curl your fingers into a loose fist shape (like when you slap, as well), with your fingers pointing back toward you. The side of the anchor facing away from the neck becomes a handy place to rest your fingers on.
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Sounds to me like an excuse.

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