A sinkhole
A sinkhole forms.
The roof of a cave is referred to as the "ceiling" or "overhang".
A sinkhole is formed when the roof of a cave collapses.
Stalactites form at the roof of the cave. These are mineral deposits that hang from the ceiling and are typically made of calcium carbonate. They form as water containing dissolved minerals drips from the roof and the minerals gradually accumulate over time, creating the elongated formations known as stalactites.
It depends on where the cave was...
Stalactite
No, a stalagmite forms on the cave floor when mineral-rich water drips and deposits sediment, creating a mound-like structure. On the other hand, a stalactite hangs from the cave's ceiling as mineral deposits accumulate and form a tapering, icicle-like shape.
They grow from the roof of the cave, downward.
The Palatine bone forms the posterior roof of the mouth.
Stalactites are found hanging from the roof of a cave, as opposed to stalagmites, which grow up from the floor. Remembering the difference is easy - stalactites are "tite" to the ceiling!
I would call it a cave in.