This object is a Lead Brazier (stove) that was used for cooking on ships using charcoal. The water in the double-sided walls prevented the melting of the lead. During the Hellenistic and Roman periods, these braziers enabled cooking in a wooden ship without risking setting it on fire. (from the sign in the museum)
This object was found off the coast of Israel and is on display in the Center for Nautical and Regional Archaeology at Dor on the grounds of Kibbutz Nahsholim.