Courteney Cox's daughter is officially an adult! The 57-year-old actress took to Instagram on Monday to wish Coco a big happy 18th birthday, posting a few adorable throwback pics of her only daughter, penning in the sweet tribute, "Happy 18th birthday coco! I'm so proud to be your mom. You are courageous, smart, deep, funny, unique and beautiful with the biggest heart. I can't wait to see what's next. I love you x." The "Friends" alum shares Coco with her ex-husband David Arquette.