Four years after Donkey Kong Country: Tropical Freeze’s initial debut on Wii U, Twitter user Shane Marchis has discovered a new easter egg in the game.

In the level Amid Amiss, if the player swims through a long escalating tunnel and swims backward later, they’ll find Metroid in the background.

Here’s a video showing how it works:

Here's a how-to video on seeing the Metroid cameo I discovered earlier. Works on Wii U and Switch! #Nintendo pic.twitter.com/wJWLo33HEz

— Shane (@ShaneMarchis) August 3, 2018

As to why and how this easter egg has been hidden for so many years, no one knows for sure. The easter egg appears in both the Switch and Wii U versions of the game.

What do you think? Let us know in the comments below.