Once you've completed what is considered the main goal of , having K.K. Slider perform on your island, you'll unlock many new features, including Gyroids.
To gain access to these musical items, you'll need to embark on your first boat ride with Kapp'n, most likely to look for Brewster, where you'll be able to find Gyroid fragments buried on an island.
Once you've dug up the fragments on the island, take them home where you can re-bury and water them. If you've done this correctly, you'll see a bit of steam coming from the buried fragment.
The next day, you'll find 1 of 36 possible Gyroid types, fully intact, to collect and display. Each one features a unique design and sound, but some are more memorable than others.
Of the 36 different Gyroid options in , only a handful have a wide range of color variants, and even fewer offer options with bright colors.