Another possibility could be a net, IMAO. Some extant invertebrates build similar structures. > may represent a dikaryotic fungus in marginal marine ... fluvia

Another possibility could be a net, IMAO. Some extant invertebrates build similar structures. > may represent a dikaryotic fungus in marginal marine ... fluvial or lacustrine environments. As I thought, yep. Water. I would suggest them to read about Ascidian mucus-net feeders. A similar solution. Would explain also a world without predators, where everybody is busy sit in the same place grazing bacteria. Looks like a good opportunity for having filterers also but... where are them? maybe those animals expanded its range with temporary mucus nets? Just one hypothesis.