Thanks for the comments guys.
The green cube to the left stores a handful of Java moss. The critters love the Java moss, but I don't like it in the tank because it gets messy.
Whenever I have critters to acclimate, I put Java moss into their bowls for them to hide under. Currently, a small shrimp fry resides in that cube. He's too small to go in the big cube. He might get eaten.
The clear cube on the right just stores some miscellaneous loose plants. Got some Fissiden and Pelia in there.