Stone pillar formed when stalactite and stalagmite meet, or when stalactite reaches the floor of the cave.
A pillar a column or sometimes a stalagnate.
A column of a cave, also known as a stalagnate, is a geological formation created by the gradual deposition of minerals from dripping water over time. It forms when stalactites, which hang from the ceiling, and stalagmites, which grow up from the floor, meet and fuse together. These formations are primarily made of calcite, a mineral that precipitates out of mineral-rich water. Columns can vary in size and shape, contributing to the unique beauty of cave environments.