Bell jar

A bell jar is a piece of laboratory equipment similar in shape to a bell.

In 1996, during the Battle of the Department of Mysteries, Harry, Hermione, Ron, Ginny, Luna and Neville saw a towering size crystal bell jar stood inside the Time Chamber. It producing a dancing, diamond-bright light which caught the attention of Harry Potter. Drifting along in the sparkling current inside was a tiny, jewel-bright egg. As the egg rose in the jar, it cracked open and a hummingbird emerged, which was carried to the very top of the jar, but as it fell on the draught its feathers became bedraggled and damp again, and by the time it had been borne back to the bottom of the jar it had been enclosed once more in its egg and then the egg's hatching and unhatching, repeatedly.

Later, in the battle. One of the Death Eaters who attacked them are accidentally got stuck his head through the bell jar after Hermione used the Stunning Spell on him. The Death Eater's head suddenly turns into its baby figure, as he struggled to get up again, the head comeback to its previous proportions, but before he could pull himself together, the head began to shrink back to babyhood once more. While seeing this, Hermione says: It's time.., Time....