D&D 5e Road Test
Ancient Dwarven Sphere
This grapefruit sized stone sphere weights approximately 10 pounds and seems to be of dwarven manufacture.
When thrown at a surface made of stone, it will pass through the surface emerging instantly any nearby surface made of similar stone, at the same speed and relative direction as it entered the original surface. Directing the sphere seems intuitive and thrower can will which surface they wish the sphere to exist without so much as thought.
If the stone is willed to a surface it cannot reach, or no such surface is nearby it will simply bounce off of or embed in the surface with no particular indication or consistency as to how or why.