Help Identifying Cob

[Cameron K]

Great to find this forum! I picked this up in a 'mystery box' recently, and initially thought it was an ancient coin. However, the friendly folks at Forum Ancient Coins clued me in to it possibly being a Spanish cob. I'm hoping someone here might recognize it and help me narrow down what kind it is.

I've brightened it up about 60% in photo shop. It's grey in actual appearance, 17mm square and 'pings' like silver when dropped on a table.

Thanks in advance for advice and for taking a look!