One hundred years ago this week, a baker named Alma Crust mixed flour and water in a crock and set it on a windowsill. The crock is gone. The windowsill is gone. The bakery has burned down once, flooded twice, and changed hands five times. The starter persists.

“Bubbles has seen things,” said current owner Sage Millstone, feeding the starter its birthday meal of organic rye at a small ceremony Tuesday. “You don’t survive a century in this town without developing a certain depth of character. You can taste it. It’s the tang.”

The starter’s longevity survived its greatest test in 1987, during the Great Bakery Feud, when co-owners split the business and each claimed custody. A judge famously ruled the starter be divided in half, noting in his decision that “unlike most things brought before this court, it will grow back.”

Both halves thrived, and when the rival bakeries merged again in 2003, the starters were ceremonially recombined in what longtime residents still call “the reunification.”

Birthday celebrations continue through Sunday, when the bakery will give away one hundred loaves. Residents are advised the line already exists.