We’re not going to pass up a chance to celebrate a Lego milestone! They celebrated the 60th anniversary of their world famous plastic-studded brick earlier this year with a handful of play sets, and now they’re in line for another anniversary celebration! 2018 marks 40 years of the minifigures that have been at the heart of so many dreamed-up Lego adventures over the years, and to mark the occasion, 16 new 40th Anniversary Lego Minifigures are being released in mystery bags starting April 1. Oh, and there’s one more surprise — a re-release of the first minifigure ever produced!

Officially called the Party Series, the new minifigs are filled with wild costumes — looks fun! If you’re a minifig vet, you know the drill, but for everyone else, here’s how you’ll get your hands on these guys. Lego regularly releases sets of 16 minifigures, then sells them one-by-one in mystery bags that you can find online or in stores for $3.99. So yeah, you don’t know what you’re getting when you buy — it’s as devastatingly effective a scheme as it sounds, especially if you really, really want to collect all 16. Or, 17 in this case, thanks to this guy!

Here’s the man of the month! The police officer was the first minifigure ever created. He arrived on the scene in 1978 along with the Police Car set, but he wasn’t the first Lego guy ever. Before 1978, Lego did have something resembling minifigures, but they lacked faces, poseable limbs, and, most importantly, those accessory-friendly hands. Unsurprisingly, he’ll be harder to track down — with every mystery bag you’ll have a 1-in-60 chance of him making an appearance.

Next up: The 16 new minifigs you’ll be collecting!