Tori Spelling and Dean McDermott are celebrating their oldest on his special day.

The former couple both shared messages on Instagram for their son Liam as they celebrated his 18th birthday, taking a minute to reflect on how much their son has grown up. Spelling, 51, shared a series of photos of Liam throughout the years, beginning with a selfie of herself and the teenager, who sported red hair.

"It’s official my 1st born is an adult…" Spelling began her lengthy caption. "They say don’t blink because they grow but no one prepares you for how fast it goes. 18 years ago today my beautiful Liam Aaron McDermott aka Monkey made me a mama."

The podcaster went on to say that Liam was the easiest baby ever and gave her a purpose in her life.

"It’s a hefty weight being the oldest of five. A lot of responsibility that you’ve proven over and over to take on gallantly," Spelling wrote. "The way you’ve stepped in to protect me emotionally shows how love has no boundaries."

"You will always be my baby. While I cannot physically hold you in my lap anymore with arms wrapped around you know that my heart is forever wrapped around you," she wrote later on. "I cannot wait to see where this journey leads you."