If you've frequented Gas Works Park in the past week, you may have noticed a new addition to Kite Hill — a vintage aerobics bike that seems to have spontaneously materialized.

Where did it come from? How did someone even lug that thing all the way up there? Was it aliens?

Honestly, we don't know. But it's the most Seattle thing ever. Even more Seattle? A local recently took it upon themselves to turn the mysterious addition into an interactive community project.

Austin Hirsh has been hiding "secret photo booths" around Seattle for the past month, and Gas Works Park's mysterious bike made No. 14.

Editor's Note: We double checked over the weekend and while the random bike was still in action, we couldn't find the secret film reel. However, Hirsh regularly checks the sites every few days so it may make another appearance.NICE

The mysterious bike isn't Gas Works Park's only secret photo booth... | Photo by SEAtoday staff

Down for an adventure? Hunt down the rest of these hidden photo booths. Here's how it works:

Tap your phone against the affixed film roll to "unlock" a mobile photo booth.
Enter in the prompted password (you'll receive it when you "tap").
While in the "photo booth" on your phone, take a selfie from atop the aerobics bike (or a pic of the gorgeous view if you're camera shy and curious).
Your pic will be added to a virtual "reel" of others' pictures from that very spot.

The used film rolls come from Seattle's own Panda Lab, which Hirsh then embedded with tiny NFC chips. These little chips help wirelessly transfer the secret photo booth to users' phones.