I keep finding this old dog can learn new tricks—or, if not quite new, ones that were hiding in plain sight. The other night, using Messages on my iPhone to send a good-night text to my spouse and older child, off on a brief getaway to the coast, I noticed that orange highlighting had invaded my message!

I text a couple of friends: “Have you seen this before?” One had not; the other remembered it vaguely, but had no idea why it had occurred. Some googling later, I discovered that Apple had added the feature recently…on the geologic scale. This feature, which I’ll explain in greater depth, first appeared in iOS 10, released in fall 2016.

Well.

The orange-highlight emoji replacement feature in iOS Messages turns words that match emoji names into tapping targets from which you can select an appropriate symbol.

Here’s how it works: