Include an "at" symbol ("@") in a text cell

I'm organizing some stuff in a spreadsheet. None of it should be interpreted as anything other than than text, but it does contain a lot of non-alphanumeric characters.

If I include the character @ in a cell, then that whole word turns blue, and I can no longer delete/change characters within the word. The whole word acts like a single character. Also while I'm editing that cell's contents, the word will have a grey background, making it very hard to read.

(My cursor is in the last of those cells, it just doesn't show up in the screenshot.)

What is this?
How do I stop it?

Solution 1:

1. Go to Tools -> AutoCorrect Options -> Options
2. Uncheck URL Recognition
3. Press OK.