Crystal Caves is a bright, beautiful world accessible from the ladder in the Sprout Desert.
Features
This area is a vast, looping system of caves filled with purple crystals of varying sizes, where the background contains a large cluster of crystals over a Lorenz attractor. There are many points of interest scattered about, including a strange monster at he edge of one section, a cave that is currently blocked off, and another long ladder leading down to a beach, from which you can get to the bedroom in Lullaby Land.
As you explore, you may encounter dead ends with sets of two identical crystal structures, where going in between them will teleport you to the crossroads. Here you can find a huge, spiraling dragon statue. Taking the northern path leads to the Stellar Lake.
Stellar Lake
This area starts off with a small island, where you can use the Mermaid effect to traverse a straightforward path with multiple arches reflected in the water. On the other side of the lake is another island with smaller counterparts of the star-like structures from the lake all over the place. The northernmost section of this island houses an altar with a large, crystalline flower-like object.
Directions
Totsutsuki's Nexus → Broken World → Sprout Desert → Crystal Caves
Trivia
This world was originally in Yume 2kki before the author moved it to Uneven Dream.