Continuing with the structural features that can alter the shape of rooms, here are modified ceilings, with side views.
Crossbeams: Or rafters, joists, or other horizontal structures just below the ceiling. These may actually support the ceiling, or they may be lower, allowing enemies to crouch on them and hide in the shadows. This can also include elements that don't provide support for the ceiling or walls, such as pipes or ducts crossing through the room.
Domed or Vaulted Ceiling: This usually means the center of the ceiling is higher than the edges. Rounded or vaulted shapes provide better support for large ceilings, so these rooms can be a little larger than normal; they also provide space for tall structures in the room.
Jagged Ceiling: The ceiling is either broken or juts down low naturally, possibly forcing those traveling through the narrow part to stoop. Since it drops lower than normal, there may also be dangerous substances clinging to the surface to deal with, such as green slime.
Open Ceiling: There is no ceiling, or there are only remnants of the former ceiling. This can extend up to the next level or to the surface; a natural shaft may act as a cliff face for flying creatures to perch, waiting to ambush if disturbed or hungry.
Vent: A smaller hole than the completely open ceiling. It can extend up to the next level or to the surface, as above, or it can connect to ducts or pipes embedded in the ceiling. It may be open, allowing access to the ducts, or it may have a grate that must be removed. Like the Depressed Floor, the location of the die can provide the first letter of the substance that passes through the vent; you can have water, sewage, air, heat, or poison gas spewing from it to those below. If the flow is low and the vent leads to the surface, you may be able to see daylight.
Sloped Ceiling: Like the Sloped Floor, this ceiling rises at a slant to a higher point. This may indicate that the ceiling in the next room is at a higher level, or it may be a sign that the ceiling has shifted after a massive quake (especially if combined with Collapsed Wall or Jagged Ceiling.) Rivulets of moisture may be seeping down the slope.