[OR] Invalid Element error

I encountered the dreaded red circle with the white X. Fortunately and surprisingly, I was able to click it, and got its element information. It appears to be on a drainage cross section level, but I wouldn't expect such an element in this file, so I don't know what it is, where it came from, and no information of how to fix it.

I'll be honest: I'd be willing to delete it, but it won't accept the delete command. It had some handles that looked like I could move it, so I clicked one of them. I moved the cursor around but didn't see anything of note. I sent the datapoint. It vanished. I have no idea what happened here.

The tip isn't exactly helpful. Can we get better explanations for what's wrong with an element like this? Like elements that it had been derived from, etc. 

It may be worth noting that I expanded the entry in the element information. It gave me "Depends On". The only ancestor is an unnamed line. This line is 4' long, so I have some idea of where it came from but it could be one of two lines. Right-clicking and zooming to it, it zooms to the new location of that element (I had moved it recently). So why didn't this error element go with it?