Marian Robinson, mother of former First Lady Michelle Obama, has died at age 86, the family announced Friday. She passed away peacefully in the morning, according to a statement.

Michelle Obama shared a heartfelt tribute on social media, calling her mother “my rock.” She wrote: “She was there for whatever I needed—the same steady support for our whole family. We’re heartbroken to lose her today.”

Former President Barack Obama also honored his mother-in-law online, calling her one-of-a-kind. “We feel lucky to have had her in our lives,” he posted. “We’ll spend our years trying to live by her example.”