They have been artificially conserved by those strange accidental conditions."

An accidental condition that causes a functional unit to fail to perform its required function.

We can't depend on our moods or the accidental conditions of our miserable bodies.

You state that nuclear installations are designed and built to contain virtually all the byproducts of their operation, even under accidental conditions.

This was no accidental condition, following wholly from some alleged natural benightedness of the backdunes, but one which required constant vigilance and determination.

It is thought that natural pearls form under a set of accidental conditions when a microscopic intruder or parasite enters a bivalve mollusk, and settles inside the shell.