It is an extra special week for Ashlee Simpson and her family.
On Thursday, November 21, the "Pieces of Me" singer celebrated her eldest son Bronx's milestone 16th birthday, and he really is so grown up.
The doting mom shares the birthday boy with her ex-husband Pete Wentz, and in addition to him, also shares daughter Jagger Snow, eight, and son Ziggy Blu, who just turned four, with her husband Evan Ross, with whom she just celebrated her milestone tenth wedding anniversary.
In honor of Bronx's special day, Ashlee took to Instagram and shared a round of photos from his birthday celebrations as well as sweet photos of him through the years, and left her fans in disbelief over how grown up — and super tall — he is already.
In the first snap, the two are posing side-by-side, Bronx towering over his famous mom, then some of the next photos are of her baby bump, Bronx as a newborn and toddler, plus of him doting on his younger half-siblings.
"Being your mom has been the greatest joy of my life. You are my rock, my soul. My ride or die," Ashlee first wrote in her caption, adding: "You have been the greatest blessing in life that I could have ever dreamed of. I would not be me without you."
She went on: "You are so calm, consistent, brilliant, loving, kind hearted, thoughtful, funny, mysterious, and incredibly awesome. I thank God every day that I get to be your mom."
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"You are a true gift to this universe and I'm so lucky you are my very grown, and cool baby… happy 16th birthday. I love you," she concluded, lastly noting: "Also you were born to this song. Thank you for making me the luckiest," referring to the song on the post, "Redemption Song" from Bob Marley & The Wailers.
Fans were then quick to take to the comments section under the post and gush over it, though first Bronx's aunt, Tracee Ellis Ross, Diana Ross' daughter, wrote: "Happy Birthday BRONX. Love you."
MORE: Ashlee Simpson's son Bronx, 15, towers over her and stepdad Evan Ross in rare family outing
Others followed suit with: "Happy birthday Bronx!!! I can't believe how grown up he is!!!" and: "Wow, he's so big!" as well as: "Happy 16th birthday Pete Wentz Jr!!" plus another added: "He legit is @petewentz's doppelganger."
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Pete himself also shared a sweet tribute to his son, posting a selfie of the two together on his Instagram Stories, and writing: "Happy birthday love you so much."
Since his divorce from Ashlee in 2011, the Fall Out Boy singer has been in a relationship with model Meagan Camper, and they share two kids together, a son born in 2014 and a daughter born in 2018.