This visual puzzle is filled with rows of black plus signs, but one symbol breaks the pattern.
Instead of staring at the whole grid, scan each row from left to right. The repeated plus signs make it surprisingly easy for your eyes to glide past the odd symbol.
The symbol that does not belong is the X in the fourth row, sixth position from the left.
Once you notice it, it becomes obvious — but before that, the repeating pattern can hide it very effectively.
Answer: the X.


