Is this an original early Sheave bearing??

[Tiefel]

Hi all! New to this group and I'm hungry to learn about the history of sailing ships.. I found this on a beach in the Caribbean, was originally a complete green color probably do to the copper content within everything..  I was wondering if this is an actual sheave bearing? All brass on the outer and bronze bearings in the center. Looks to be hand made originally with the non-concentric bronze needle sleeves. Let me know your thoughts and if so what time period.. Also maybe a link to the history on such early linear bearings? Also what the heck is this bronze/brass ball piece might have been to? It has a small hinge fold on the underside..  Thanks!