Aniseed ball

Aniseed balls are a comfit type of hard round sweet sold in the United Kingdom, Ireland, Malta, South Africa, Canada, New Zealand, and Australia.

They are shiny and dark reddish brown, and hard like Gobstoppers, but generally only 1⁄2 inch (13 mm) across.

In the spring of 1939, a magnetically attached limpet mine was constructed in Britain for underwater sabotage actions in the upcoming war.

The mines exploded when a cocked spring hit a detonator.

Between the striker and the detonator an aniseed ball was placed, as each had precisely the same spherical shape and consistently dissolved in water after 35 minutes, leaving the saboteur time to escape.