Let us help you identify that mysterious object you’ve found.
Currently in CHALLENGE mode: If you've got something obscure knocking about, post a picture, and let's see how we do. Please prefix such posts with "CHALLENGE:" so we know we've got a fighting chance.
[Solvex: EcoBee Smart Sensor]
About 4cm, powered by CR2477 batteries.
Edit. Found another one, and this one had the top off.
The logo is for Ecobee, they do smart home stuff like thermostats and doorbells. That specifically looks like one of their smart sensors
Yep! Specifically, this is likely a temperature and occupancy sensor meant for use in conjunction with their smart thermostats. Something pretty similar to this: https://a.co/d/0g0CuprM
Looks like that's it! Thank you!!
100% an Ecobee remote sensor. Connects to a thermostat, totally benign.
I'd say the central component in the opened pic is a https://en.wikipedia.org/wiki/Pyroelectricity (PIR) sensor. Often used for detecting motion, but some models at least can do more.