Hi!
Unsure exactly what it is as I am not a professional by any means, but I do have an interest in Spanish coins. To me, this definitely looks like it is some kind of Maravedis cob coin, as that most definitely looks like the monogram of Felipe, or Philip, IV. See here for an example. If memory serves me right, these coins were made by hammering pieces of copper bars between two dies which would quite often break so the coin comes out in interesting shapes, hence why some of the shape has been cut off. I hope this provided some useful insight, but hopefully someone else will be able to help with the exact identification of the coin, instead of the vague pointer I can provide.
Best of luck with the search!
