世纪

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.

纪 = 己 + 纟 : Joan of Arc finds the space station's bathroom full of silken threads. She even cannot accomplish much using a butcher's hook. She knows that the silk worms are responsible and thinks that soon it will be the era of the silk worms.