I apologize for not being much help at the moment.. I'm on a cellphone and it's real hard to see.. but that looks like a Lima Peru minted cob.
Mabey a 2 reale.
I think the first photos are upside down.
The bottom pic needs to be rotated 180 degrees for proper alignment--so that the 'P' will be on the right side of the crest and the crown above the crest.
Don...
PS: Weight will give its denomination. Use 27 grams for an 8R; no greater than 13.5g for a 4R; 6.75g for a 2R, etc.
PPS: The 'P' at the right might suggest the assayer (name unknown) who was the assayer for Mexican silver coins salvaged from the "Concepcion" sunk in 1641.
Then again, the 'P' assayer could be Luis de Peralta (Potosi mint).
I'd suggest electrolysis to bring out more of the coin's features, including the other side which currently I cannot discern any feature to ID it.
D.