My wife "organized" one of my drawers, and this thing came up. What on earth is THAT I asked. "It is just one of your thingeys" she replied.
It had no batteries in it, so I inserted some.. and nothing happened.
A speaker, a print (with a black-blob-chip on it), and.. some strange "sensor" or something? Strange little thing with wires on each side, to hold it together? And to mystify even more, that can be "sealed off".
Also, on the side it has some mounting-part, that had some old no-longer-stickey tape on it.