(Answered, thanks) Ultra-simple, dumb noob question...

[NCD]

I keep seeing some basses with what is apparently an optional rest of some kind that's screwed into place so that's it's on the pick guard to the right of the G string (on a right handed bass).

Neither of my basses have it and a search on Google for anatomy of a bass only showed basses that didn't have it either. If it were a rest I'd have expected it to be for the thumb, but this clearly isn't the case since it's on the wrong side.

What is it and what's it for?

There is a good look at a bass with it here:

Pawn shop find!!

[Truktek2]

It's a tugbar. A place to anchor your fingers as you pull your thumb across the strings. Kinda opposite of a thumbrest where you would rest your thumb while you pull your fingers across the strings.

[NCD]

Okayyy... I've seen a few references to times that you may want to use a thumb but I'd imagine that it's more of a holdover from 6 string guitars.

Thanks for the answer, I'll file it in the "Things I don't need to worry about yet" part of my brain.

[walterw]

it's not a holdover from guitars, but from the original design of the fender bass in the '50s.

remember, this was basically a whole new instrument, and nobody really knew how it would come to be played. thus the tugbar, put there on the goofy premise that players would hold it with their fingers and thump the strings with their thumb.

now you see them just because they just look "vintage". (my P-bass has one for no other reason )

[Pilgrim]

Search "tugbar" here on TB and you'll find tons of info, including a history of the item.