活火山

活 = 氵 + 舌 : Helga Horse joined the traditional water bottle challenge and empties a bottle of water over herself in the observatory's kitchen. To raise the difficulty level, she only uses her tongue to hold the bottle.

火 = 人 + 丶 : Helga Horse (hu) and Neanderthal Man (人) are starting a fire (火) in the observatory's living room (o3) with two large petals (丶).

山 = 丨 + 凵 : Mnemonic symbol: 山 looks like the tip of a fork. Sherlock Holmes (sh) is climbing a mountain (山) in front of the anthill (an1). He uses a dinosaur bone (〡) as walking stick, and to have better grip he attached a fork (山) to its tip. Unfortunately he accidentally sticks the fork into a receptacle (凵) on the ground of the mountain and gets shocked.