橡木

橡 = 木 + 象 : Marie Curie (xi) wants to plant some oaks (橡) in the anglepod's bathroom (ang4), so she had the KFNB Elephant (象) transport young oaks to the bathroom. In exchange she provides the train with a lot of Christmas trees (木) to be used as fuel for the steam engine.

木 = 八 + 十 : Mnemonic symbol: a Christmas tree.

Malte Monkey (mu) is setting up a Christmas tree (木) in the bathroom of the space station (Ø4). He decorates the tree with eight-balls (八) and puts a holy cross (十) at the top of the tree.