Diatomaceous earth (珪藻土）is a naturally occuring sedimentary rock comprised of dead planktons or green algae.
(c) Yogo Homes
It can be mixed with other materials (i.e. lime) to make an extremely porous wall paste.
That means…this wall sucks up excess humidity and releases moisture back into the air when the room is dry!
(c) Hideki Takayama Architect Office Inc.
People are said to be comfortable in humidity level between 40~70%; diatomaceous earth walls maintain humidity level of around 60%.
Other properties: removes odor, maintains temperature, soundproofing