Kate Hudson shares rare photo of her growing sons

Kate Hudson's sons are getting so big!

The "Almost Famous" actress took to Instagram late on Sunday night to wish her youngest son, Bingham Hawn Bellamy, a happy birthday with an adorable photo of him posing with his older brother, Ryder Robinson, 13.

SEE ALSO: Harper Beckham celebrates her birthday in princess dress at Buckingham Palace with Princess Beatrice: Pics!

The boys are all smiles as they pose next to Bing's Spider-Man-themed birthday cake.

"Oh how they grow!" Hudson captioned the picture. "Mr Bing Bong turned a big 6 today."

Hudson shares Bingham with ex-fiancé, Muse frontman Matt Bellamy, while she shares Ryder with ex Chris Robinson. She maintains a friendly relationship with Bellamy, too: Back in February, the actress took her sons to a Twenty-One Pilots concert with her ex -- more on that in the video above!

See more photos of Kate Hudson and her sons:

The photo is an extremely rare instance of Hudson posting a direct image of her children. The protective mother usually covers her kids' faces with emojis when posting to social media, as to protect their privacy. While we love that Hudson tends to keep her boys anonymous, this little peak at her kids was a much-welcome surprise!

Hudson is currently dating Chief musician Danny Fujikawa. The cute couple made their first public appearance together back in May at the premiere of Hudson's mom Goldie Hawn's movie "Snatched." The pair adorably packed on the PDA for the cameras.

See photos of Kate Hudson and Danny Fujikawa at the "Snatched" premiere:

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