This is a grappling hook (*kaginawa*) from the Edo period.
You can clearly see the marks left by Edo-period artisans as they repeatedly hammered the metal to securely bond the four prongs.
Height: 14.5 cm; Prong width: 14 cm (Note: measurements may vary slightly depending on the point and method of measurement).
It is made of iron. Please note that there are signs of rust, dirt, and wear due to age.