The world was shocked when he was unexpectedly killed in action.

But now many of Steve Irwin 's fans will struggle to believe that its been ten years - to the day - since the Australian star died.

To mark the sombre annivesary, his daughter Bindi took to Twitter on Sunday to celebrate her father's personal and professional legacy.

Sharing a photograph of herself with the wildlife expert, she described him as being "my hero for my entire existence."

(Image: Twitter@BindiIrwin)

Clearly proud of her father, she then added: "I love you more than words can describe."

Unsurprisingly, the image - which shows Steve holding new-born Bindi aloft with one hand - garnered more than 29,000 'likes' in just 15 hours.

It was also re-tweeted on Twitter more than 11,000 times.

Getting philosophical, she simultaneously posted a quote from the Dalai Lama which read: "Happiness is not something ready made. It comes from your own actions."

The sweet gesture comes just days after it was revealed the late TV star reached out to parents Lyn and Bob them from beyond the grave in a previously-undiscovered letter.

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The late TV star shared a message of love in the touching missive, which was fatefully found by his father in the jacket of a book.

Addressing both parents, the heartfelt message begins: "Probably one of the most unfortunate things in a 'bloke's life' is that it takes over 30 years to realise how essential you have been to build my character, my ethics and, most importantly, my HAPPINESS."

It continues: "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!"

(Image: PA)

(Image: Getty)

The hand-written note was enclosed in an envelope which read: "Please be happy to know that your strength and wisdom have been passed on."

It will be published in forthcoming memoir The Last Crocodile hunter: A Father and Son Legacy, later this year - just over a decade since his passing.

Sadly, Steve passed away when his heart was pierced by a stingray barb while filming a TV project.