Bindi and Terri Honor Steve Irwin on 10th Anniversary of His Death

The Crocodile Hunter's daughter Bindi, 18, took to Instagram to remember her dad with a photo of the wildlife expert holding her as a baby. She wrote, “You'll be my hero for my entire existence. I love you more than words can describe.”

Her mother Terri also remembered Steve with a Twitter pic of Bindi and brother Robert with their father. She included the caption, “Happy Father's Day Australia. Hug your dad.”

Bindi was 8, and Robert, 2, when Irwin passed away while filming a documentary.

Last week, Steve's dad, Bob Irwin, shared a letter the TV star wrote to his parents years before his death. Bob revealed he didn't find the note until earlier this year.

In the letter, written 12 years before his death, Steve wrote, "Probably one of the most unfortunate things in a 'Bloke's Life' is that it takes over 30 years to realize how essential you have been to build my character, my ethics and, most importantly, my HAPPINESS. At 32, I am finally starting to figure it out. In good times and in bad, you were there. Your strength and endurance to raise me will not go unrewarded. My love for you is my strength! For the rest of my life I will reflect on the unbelievably GREAT times we've shared and will continue to share. You're my best friends!"

The envelope holding the letter, said, “Please be happy to know that your strength and wisdom have been passed on.”