I repair laser tag vests and on the phaser board is a strange component on what appears to be the phaserboard. See the black box on the center of the bottom, close to the left edge of the ribbon cable.
It has no reliably measurable resistance and as far as I can tell is involved in power delivery, as when it falls off (which it does often) the phaserboard no longer gets power. It has a marking on the top saying "100k" but nothing else. I would like to know what it is so I don't depend on trying to find it when it falls off and can just order new ones.
Edit: It would appear from answers that it is an inductor of some kind. During my next shift I'll try to get some closer, higher quality photos to see if we can narrow down, since I've combed through DigiKey and haven't found any matches I'm comfortable with.