Glad you asked, Copago! It's a Balance Arm Sensor Unit. It's sitting in a propagating bed with bottom heat where I sprout seeds or grow cuttings. When the mesh "leaf" on the left side dries out, it rises in see-saw fashion and a fine water mist cuts in. The weight of the mist causes the leaf to sink again and shut off the water.
Your camp oven has set me reminiscing! I used to do animal survey work with a diverse and interesting group of people. Sometimes we spent days in remote bush locations. Always my trusty (and heavy) camp oven came along, later to be joined by a smaller version. Everyone was responsible for his/her own meals, but "regulars" would plan one big camp-fire meal per trip which I usually cooked. (The cook was exempted from the afternoon task of opening the traps, and anyway it was MY camp oven!)
Over the years, we had magnificent roasts or stews and in the smaller oven I could do baked apples or golden dumplings.
And yes, dampers! I always took a jar of home-made jam to pass around. Gee, I miss those days.