古新世

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.

新 = 亲 + 斤 : Marie Curie and her bride are inspecting their wedding presents in front of the encampment. There's a brand new pair of barbells packed in plastic foil.

世 = 廿 + L : Mnemonic symbol: the WTO or WHO.

Sherlock Holmes (sh) is cleaning a flower pot (廿) under the shower of the space station's bathroom (Ø4) with a loofah (L) because he didn't quite understand a poster next to the shower from the WHO (世) explaining dangers arising from different germs.

In this case, L is for loofah.