The shard's gravity field is unusual. Having once been a part of a spherical planet, it retains its former gravitational field so that gravity is directed from its rounded top down toward the pointed end of the cone, once at the core of the shard's world. This arrangement allows life to exist on the shard's top surface if there are mountains or walls ringing the edges of the top surface to prevent the loss of its atmosphere, or if there is a deep valley or crater on top in which an atmosphere can be kept. The lower part of the shard remains in the negative gravity field and is therefore devoid of any atmosphere. Like spheres, cylinder worlds can retain their own atmospheres, though walking from the rounded side to a flat side is very disorienting.
Cylinders can spin along their long axes, producing day and night if oriented properly.
Cylinder worlds, like disk worlds, are easy to map. Air can easily be trapped in a ship's hull, provided the hull is airtight. Unfortunately, the air on the deck slowly flows downward off the deck and into space. The spell-caster conveniently determines the exact shape of the breathable area. For example, thanks to the spell, an 80'x10'x10' area on the deck could become breathable.