古生物学

古 = 十 + 口 : Mnemonic symbol: at least on German maps, this character actually resembles a cloister.

Oh no! Gitta Giraffe (gu) found that the golden cross (十) broke off of the cloister (古) in the space station's living room (Ø3)! She skewers a mandarin (口) on top of the cloister so that she can skewer the broken off cross back on to fix it.

生 = 牛 + 一 : Mnemonic symbol: a cradle.

Sherlock Holmes (sh) comforts a crying baby bull (牛) in a cradle (生) in front of the engine ((e)ng1) and plays him a tune on a flute (一).

物 = 勿 + 牛 : Willy Walrus (w) wants to become a physicist (物) and does research about dark matter (物) in the space station's bathroom (Ø4). His motivation is to become a super villain and rule the world. Just as he is about to have a breakthrough, a huge black ox (牛) flying with the help of bat wings (勿) hits Willy with an oxerang and takes away the dark matter, saving the world.

学 = 小 + 冖 + 子 : Xu Xian wants to study scienceology and learn more about daisies. Just inside the elevator's kitchen, he put some daisies into a prize cup and covered them with a cooking top. He wants to study the growth rate of the daisies depending on the pH of the water in the prize cup.