What's a good Android app for, well, seeing if you've crossed paths with someone interesting during your day-to-day life?

So, my students were telling me about this app, happn. The idea is, it shows you people you've physically been near during the day. Like, if you frequent the same coffee shop or, say, you're at the same school events. It's surprisingly intuitive once you get the hang of it. It uses location services, of course, and that's where I got a little tripped up at first – why do they hide the settings button there? But once you allow it to track your whereabouts (in a reasonable way, of course, I'm not looking to be followed!), it starts showing you profiles of people you've crossed paths with. It’s a bit like real life meeting, but with a digital introduction. I imagine it could be useful for someone who, perhaps, doesn't have as many opportunities to meet new people in their usual routine. It's like having a teaching assistant in your pocket, but for your social life, ha!