Termite mushrooms!

Mushroom fruiting from a subterranean termite "fungus farm." Certain species of termites (there are at least half a dozen species in the Sakaerat biosphere reserve) feed leaf litter to a mass of fungal mycelium and harvest small lumps from the farm. The coevolutionary relationships and history of the termites+Termitomyces fungi are quite complex, but generally the two are in an obligate symbiosis--that is, the termite can't survive without the fungus, and the fungus can't survive without the termite.

While Termitomyces do have somewhat distinctive morphology, to absolutely identify them as such and to see which species of termite they are associating with the farm and stipe of the fruiting body are carefully excavated.

A different species of Termitomyces. For this species of termite, the farms are in multiple small chambers. Most of the time, the farm exists in this form. The formation of a mushroom is an irregular occurrence, and the presence of a mushroom may indicate that the farm wasn't harvested enough or the termite colony as died off.

Yet another species. These "farms" are larger. 

The small white lumps are almost ready to be harvested. 

The brown mushrooms on the left are a species of Termitomyces (called "Het Kohn") for sale at a roadside stand. They are sought-after culinary mushrooms and demand high prices, largely because people aren't as good as the termites at cultivating Termitomyces.

Many thanks to termite researcher Dr. Yamada, who took me out to see the local termites and Termitomyces.