A centuries-old hand grenade that may date back to the time of the crusaders is among a host of treasures retrieved from the sea in Israel.

The metal artifacts, some of which are more than 3,500 years old, were found over a period of years by the late Marcel Mazliah, a worker at the Hadera power plant in northern Israel.

Mazliah’s family recently presented the treasures to the Israel Antiquities Authority. Experts, who were surprised by the haul, think that the objects probably fell overboard from a medieval metal merchant’s ship.

The hand grenade was a common weapon in Israel during the Crusader era, which began in the 11th century and lasted until the 13th century, according to the Israel Antiquities Authority. Grenades were also used 12th and 13th century Ayyubid period and the Mamluk era, which ran from the 13th to the 16th century, experts say.

Haaretz reports that early grenades were often used to disperse burning flammable liquid. However, some experts believe that so-called ancient grenades were actually used to contain perfume.

The oldest items found in the sea by Mazliah are a toggle pin and the head of a knife from the Middle Bronze, which date back more than 3,500 years. Ayala Lester, a curator at the Israel Antiquities Authority, explained that other items, such as two mortars, two pestles and candlestick fragments, date to the 11th-century Fatimid period. “The items were apparently manufactured in Syria and were brought to Israel,” she said, in a statement. “The finds are evidence of the metal trade that was conducted during this period.”

Experts in Israel regularly unearth fascinating sites and artifacts. Archaeologists in Western Galilee, for example, recently uncovered a 1,600-year-old ceramics workshop and a kiln. Another dig at an ancient synagogue in northern Israel revealed stunning mosaics depicting Noah’s Ark and the parting of the Red Sea.

However, the recent discovery of a 3,000-year-old graveyard in Ashkelon, hailed as a key find from the Philistine era, has sparked historical debate among archaeologists.

Follow James Rogers on Twitter @jamesjrogers.