Random brush came from nowhere

http://filesmelt.com/dl/Whatthefucksource.png

I started on a map today, and this pop out of nowhere, what the hell. This is the first time I ever messed with round ceilings, Hell, first time I messed with anything round at 32.

You can clip trough it too.

That usually happens because of a microbrush, possibly from carving?

Its probably from an invalid solid.
invalid solids are caused by one brush being concave, or a 4+ vertex face not aligning on the same plane

May we have a look at one of the 2d views?

It could be a result of an invalid solid, sounds most likely since you can clip through it and the arches look suspect, but hammer occasionally does this cute thing where it creates a brush invisible in hammer, but there when you compile, or at least it used to. I haven’t seen it happen in quite some time, but anyway that’s beside the point.

Use alt+p in hammer to check for invalid solids.

This happens to me quite alot.
I get it with random brushes on my map that are valid solids too.

Carve and vertex tool often causes this if used carelessly.

I have had them created from square brushes before. I nicknamed them ghost brushes. Find the brush that is causing it, and remake it, that should clear up the problem.

It’s from another universe

Please close Hammer, log out of Steam, shut down and burn your computer before it spreads to Hammers worldwide

OH SHIT, IT’S TOO LATE! [/caps]