Random ticking on Moto Z?

[Android Central Question]

So my sister was using her phone by me today when suddenly it started up this ticking, very much like a clock. She turned it off and set it down, but it continued the noise. After maybe ten to twenty seconds, it made a ding or chime noise. The entire sequence sounded like a timer counting down and then ringing once. It’s only happened a few times and doesn’t seem to be correlated with any specific app. Does anyone know why this might be happening, and how to stop it?

 

[anon(9533742)]

I'd be tempted to call the bomb squad.