腘

国 = 囗 + 玉 : Mnemonic symbol: a nation's flag. Let's say the Chinese flag.

In the observatory's kitchen (o2) Gitta Giraffe (gu) is practising her ballet performance. She got a whole crate (囗) full of jade bracelets (玉) and flags (国) and fixed one flag to each jade bracelet. This makes a perfect combination for throwing the ring with the flag waving behind it and catching the ring again after a few pirouettes.

月 = ⺆ + 二 : Yu the Great (yu) is modelling a moon (月) in the elevator's bathroom (e4). He uses a stapler (⺆) to staple a lot of capacitors (二) together to form a moon shape, while the real moon is sitting for him.