I was just thinking the deep thoughts of space, and the idea of alert mines came bubbling forth.

Mines that do no damage, but alert the owner if destroyed.
No idea what we'd use them for yet, but I am sure people would find uses. People are good like that.

+1

I actually like this idea. I might be tempted to toss one among regular mines. Or along a trade route. Along with that, I propose that those you are grouped with won't trigger the mines and that they also receive the alert.