Sexual ascospores form under cold conditions but natural occurrences have not been documented.

A red modification of the sulfide is formed under boiling conditions.

On Earth some organisms can survive in acidic environment, but questions remain about the possibility of life forming under such conditions.

They form by treatment of the carbonyl compound with 1,3-propanedithiol under conditions that remove water from the system.

Ozone often forms in nature under conditions where O will not react.

The armed local defence structures were formed under complicated conditions.

A double mushroom, with two levels, can be formed under certain conditions.

However, some organisms will form single-species films under certain conditions.

It is a distinctive rock type or unit which forms under certain conditions.

These minerals may have formed under wet conditions in a low-acidic environment during the early history of Mars.