The comment at Sum of strings without converting displays strangely on Firefox 33.1 on OSX 10.9.5. Look at the numeral
1 inside the parens in
Any idea why?
What is that character that got in there?
Let's take a look at the HTML:
As you can see, a
‌​ was automatically inserted by the Stack Exchange software. This has been reported on The Mother Meta (and the reason was provided by @TimStone in the comments on that question).
Seeing as I don't see the symbol on Chromium or Firefox on Ubuntu or the app on Android, it's probably a font problem.
As further evidence, the comment I've posted below should have the same strange character in it for you.