Kate Beckinsale Shares Adorable Back-to-School Pic of Lookalike Daughter Lily Sheen

They grow up so fast!

Kate Beckinsale is a proud mama, sharing a sweet photo to Instagram of her daughter Lily Sheen's last first day of school!

The cute snap shows a throwback of Lily on her first ever day of school in a baby blue uniform, side-by-side with Lily now, at 17, looking just like her famous mother.

PHOTO: Kate Beckinsale Hilariously Recreates Birth Photo With Daughter, Ex Michael Sheen

"First first day of school/last first day of school. Love you so much @lily_beckinsale," the Underworld actress wrote.

Lily is Beckinsale's daughter with her ex-boyfriend, Masters of Sex star Michael Sheen. They dated from 1995 until 2003 and have remained good friends. Even Sheen's current girlfriend, Sarah Silverman, is chill with her

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"He [Sheen] and Kate are like brother and sister," the comedian, who’s been dating Sheen since 2014, said in a 2014 interview. "I love her, she's hilarious. She's really, really cool."

Check out some more of Beckinsale's hilariousness in this video.