I have done a very foolish thing

I just wanted to measure TIR

 It doesn't look wrong; just a center in a lathe spindle. You can't see the problem unless you know how the lathe is positioned in the room.

 What I did, that I should not have done, was to insert the center in the normal way, ie; shove the thing in with a flick of the wrist.

 Now it's wedged in place - the way it would normally be if you were going to use it - but I can't get it out again.

 I can't get it out again because the lathe headstock is up against a wall, preventing me from shoving a rod down the spindle to knock out things mounted in the spindle taper, the way one normally does.

 I literally have to move the lathe before I can use it again.
Plot twist: I have no way to move the lathe at the moment.

 It might be possible to remove if I make a special tool; I can't think of a way to get it out otherwise, short of moving the lathe and doing it the normal way.  I was gonna move the thing eventually, because of this, but I wasn't ready.  Ye gods I am dumb!  One instant of forgetfulness leads to hours of headache.

EDIT, later: man, this is a huge cockup.  I can't get the 3-jaw on over the center at all, and the 4-jaw I have is kind of a PoS, although it looks like it would mount over the center.  Even if it did, the center poking up through the center bore of the chuck will certainly restrict its use.  Nothing long at all can be managed, and centering in my 4-jaw is actually worse / more impossible than in the 3-jaw because it's also a scroll, not independent-jaw. >_<

The center can't be removed with a shop-made tool because the manufacturers machined it into a cylinder between the center angle and the spindle taper, so there is nothing to pull on.  Very convenient.  Clamp friction alone isn't likely to pull it out of a Morse taper, I suspect the clamp would just slide, although there is plenty of room for a very beefy clamp indeed.  The entire center is as hard as a bad day.

 Speaking of bad days, my lathe is now unuseable and I need a day out of the house because I'm now in a fucking foul mood.