The "Mooshüsli" is at the centre of the primeval garden, which will was redesigned in 2019. Leaning against the north side of the Botanical Institute, this small greenhouse, half sunken into the ground, was probably built in the 1930s. Not much is known about its former use. It is said to have been built specifically for the study of mosses. Since the 1960s, it has served as a wintering place for potted plants. During the renovation in 2019, the earth greenhouse received new roof glazing with ventilation flap, new windows and a glass door. A lava stone wall with an irrigation system was built on the north and west walls inside.

Today, at first glance, the moss house contains inconspicuous and very old moss-like plants, lycopods and ferns.

Here a small selection of the species:

• Huperzia selago
• Hookeria lucens
• Selaginella uncinata
• Blechnum gibbum