A fully designed (rather than evolved) digital ecosystem residing in a virch. A virchology may be a copy of a ril ecosystem in a ril-like virch or an entirely unique system in one of the less ril-like virches. Examples of the latter include the five-dimensional Rubenstein prime-number colonies popular in 5d Rubensteinian virches.
Virchologies differ from embodied ecosystems in that they have to be adapted to a digital environment. A very few high-definition virches can run truly detailed ecosystems, but use various techniques to merely simulate them. In more fantastic virches the designers may not even be interested in simulating anything resembling the ril, which presents its own challenges.
Pure virchologies are designed from scratch to be stable and self-sustaining and do not usually require outside intervention to survive. If the environment changes, or the virchology is moved, intervention may be necessary, but otherwise the system should be able to run on its own. Rough virchologies are built bit by bit as new users add extra parts to the virchology. These environments may become incredibly diverse and complex with time, but the fewer restrictions there are on new contributions the greater the chance that a super-predator or parasite may be introduced to the system and the virchology die out.
The largest recorded modosophont-created pure virchology, in terms of number of species, is the Euopia virch of the F3425-34 server cluster in the Solarian League. It took the Sun Monks 1,200 years to design the 10^9 species straddling three 4-dimensionl layers of existence. The largest recorded rough virchology created solely by modosophonts is the Animals Experiment residing in a server in Alpha Centauri. With approximately 1.2*10^14 species and 10^16 entities, the Animal Experiment has been running for 8000 years with only a few updates in the code and changes of hardware. Though the origins of the code lie shrouded in legend, it is said that the original seed may date all the way back to early experiments in AI and flock simulation during the Information Age. Several virches may share the record for the greatest population of entities in a single virchology since a number of low-resolution virches claim to have an infinite number of entities within them.