what is this?

[proto]

It's diameter is 6mm and I found it on the floor of my workroom. What could it be? :?

 

[33dollars]

A rusty old locking star washer :geek:

 

[ZDP-189]

Somebody's got a screw loose.

 

[proto]

Somebody's got a screw loose.

Yes, that's me!
Sorry 33Dollars, myself I don't know what it is. It must be a part of something, perhaps of the pump of the bycicle?
Star washer is something real?

Here the back of the 6mm thingy, which looks a bit like a screw of a shovel-screw of an old ship. Here the hills seem to have been frotted against something else.

 

[ZDP-189]

33d is almost certainly correct. I would guess washing machine or dryer. Something with a spin cycle. Bottom fixing of the enclosure. And unless you had it serviced, there will be a screw missing.

 

[proto]

Great, the only machine in the room is the PC, only 6 years old. So somebody from out brought it in.
Thanks !

(star-washer, I really didn't know, what this could be before, sorry )