
- it's a piece of electronic jewelry (blinky earring, or pin);
- an old annoy-a-tron;
- or Bluetooth tag, like a Tile item finder.

She takes a photo, sends it to him, who sends it to us... via low resolution text message...
Rough guess...
A Bluetooth item finder, similar to a Tile, but a Chinese knockoff branded with some corporate logo. Possibly a promotional item?

Later we eventually received a photo of the flip side...
Hummm... not too helpful, but no evidence of on the front of a pinhole for video, or a microphone on the circuit board. No battery seen, but the two large solder tabs and circles on the circuit board indicate there is a battery on the other side of the board.
Why would someone mount something like this on a bedroom wall?!?!

Nope. Tiles have their logo on them. Ours looks different.

Could they have sent out a promotional "Tile" with their newly designed exclamation point logo on it?
Close, but no prize.
Okay, let's start fresh.
Say, the Tile is a MacGuffin.
Look elsewhere.
What other wall-warts do we know of?
HVAC sensors, for one.
Google search....
Case closed.
This was a good investigative process refresher for us, and a thing we will all remember next time "this thing" shows up.
Extra Credit:
~Kevin