Slimy Insect Real Estate

One time during a walk in the forest I came across this curious formation of slimy matter that was presumably the home of the two insects that were bustling around it. Looks cosy.
I vaguely recall posting it to some kind of insect forum with no luck, maybe someone here can recognize what it is? I wonder if it's some kind of fungus/mould, or actually constructed by some busy little creature.
I went back to the same spot about 2 weeks later and the only thing that remained was a little slimy circle.