Unidentified object in Cabo Rojo, Puerto Rico, in 1973? Anyone know anything about this?

I read in a book entitled "Curiosidades Puertorriquenas" (book in the 70's) that there was an unidentified object found here in 1973, and that the FAA, Coast Guard, and "Servicio Meterologico" were not able to identify it. Updated info, anyone -- with a link or a reference??