Pi Network is a cryptocurrency, started by Stanford Phd's. You can download an app on your phone (iOS or Android), and it takes negligible battery power to run and mine. All you need is a phone number or throwaway facebook account to sign up.
Come join and get a piece of the pi: you can find more info at the minepi website.
It has no value right now but that could change if we get enough people using the product. It isn't listed on any exchanges yet, so if you join now you will be early. There are over 1000 users so far, unsure how many are active.
Because it's still so early, you'll need an invite code to join.
Use the invite: babyshark
Thought it was sketch at first, but after reading the whitepaper it seems decent and not a scam so far. You can directly speak to the devs, as well as other uses with the app. For any interested, definitely give it a look. It's like Electroneum but better.