Fire Sprinklers

When they first came out they were all ugly. Nowadays, they cleverly don't come out until they're needed - when there's a fire - when you are guaranteed to not care about their looks:



See? You order one like this, and you set it up in a dropped office ceiling, and from below it looks like this:



Such a lovely shiny cover
for a spray-and-soak device.
It doubles as a mirror -
with no increase in price!