I'd like to replace an old, rusted light fixture on the bathroom ceiling. Unfortunately, I have no idea how it's actually held up to the ceiling. There are no screws on the sides, but there are holes. When I put my finger in to feel for a screw, it seems to only be insulation. I read that it may be spring-loaded? The whole thing does move; I can spin it counter-clockwise and clockwise, but I'm afraid to keep spinning. Is this how it comes down? Any tips are appreciated! 
Ceiling – I have an old light fixture in the bathroom with no visible screws; how to remove it from the ceiling
ceilinglight-fixture
Related Solutions
I had a very similar light, and the key was this:
Any upward pressure exerted from grabbing the glass created friction that made it not turn.
You want to touch as lightly as you can, near the edges, and try to apply rotational energy only, with no pushing up.
Unfortunately, that is roughly impossible to do if you're reaching so high that you need to press up on the glass to maintain balance. So, you still need to solve the problem of getting higher (and you should NOT climb on anything placed on a bed unless it's highly stable). But if you can get a bit closer, try less pressure, rather than more.
It feels very counter intuitive, but it helped me in a similar circumstance.
One other thing that may help, suggested by none other than @Joel Spolsky, was to try using rubber or latex gloves to allow you to produce more friction without more pressure.
Looking at the geometry, it can only be paint holding it up. I would stay away from any solvents.
I would add a second putty knife, with a stiff blade. Use a slightly larger (wider to distribute the force of the lifting blade) putty knife against the ceiling (and under the lip of the fixture). Put the stiffer, skinny blade between the wide blade and the fixture. Pry up slightly, all around the circumference of the fixture. You will break it loose.
The prybar is overkill (in the photo), but illustrates how to protect the underlying drywall. (Guess what happens if you use the prybar alone. Ask me why I know :-O)
Good plan by Christos regarding leaving the new fixture, though I believe you will succeed removing the original.
Related Topic
- Lighting – How to remove a double-ended T3 R7S bulb that isn’t spring loaded
- Wiring – Converting a Single-Bulb Light to a Dual-Bulb Light – Your Opinions Please
- How to open this bathroom light fixture with an arrow and tiny hole – Asonia Round Brushed
- How to get the glass off this ceiling fixture
- Electrical – My ceiling light won’t turn off, how to wire it up correctly? (UK)
- Ceiling – How to open this flush ceiling light to change the bulb
- Lighting – How to remove old-work ceiling light fixture box attached to conduit pipes
- Wiring – How to wire / connect a new ceiling light to this ceiling junction box
Best Answer
The nut in the center on the hollow shaft is the way the fixture is held in place that is called a hickey, yes there are multiple terms in electrical language the other electrical hickey is a pipe bender.