Chest (Corbridge hoard)

[Martialis_NL]

Yes your right there is leather, this would suggest that the box was covered before being buried (perhaps in a effort to waterproof it) rather then as a decorative feature, the large 53mm nail might suggest a wooden box for the lock mechanism on the inside of the chest (the sides of the chest seem to be about 2cm thick), most probably a sliding bolt type lock.

The lock would be something similar like this, right?

(Picture is from historicallocks.com)