How do I find spot colours in my document.

I need to convert a document to an AI file and there is an error on it telling me that there are spot colours in the document. (see first image).
I figure it will just convert them to RGB because the end output for the illustration is mostly online media.
But I can't recall selecting spot colours in any of my objects, so I am curious as to what object has the culprit spot colour, in case of any problems, but I can't seem to locate it anywhere.

Have tried Edit > Find and Find & Replace Wizard and it lists all the Colour  Pallettes, but it doesn't mention just Spot colours, and in any case, I thought all the Pantone colours are 'spot colours'. Don't know about all the others. 
Can anyone shed any light on this please?