We'll keep track of them for you, too.
Tap that button and you get an account on the Stellar testnet containing 10,000 XLM.
While building Superluminal I kept forgetting if the friendbot query param was acount_id, account, or addr (it's addr).
Now that it's ridiculously easy to get test lumens we don't want friendbot to run out too quickly. Returning your test XLM means you're doing your part to help SDF spend less time on testnet restarts and more time on building great stuff.
They are cool! They're supplied by a great service called Robohash, which generates a unique robot image from any piece of data (within reason, I mean there's a finite number of part designs so there has to be a collision at some point.)
They're perfect for giving Stellar account IDs some personality, and an easier way for humans to recognize them.
My name's Zack, some people call me ZK. You can find out more about me here.