The anchor is one of two situated in Far North Queensland on the Great Detached Reef. It is likely to be from the shipwreck Charles Eaton circa 1810 - 1830.

The Charles Eaton was wrecked on 15th August 1834 but for more than a year, nothing was heard of her passengers and crew. Gradually word started to spread in many and scattered countries that some were still alive but in captivity as slaves. Two ships were commanded by the Lords Commissioners of the Admiralty to ascertain the fate of the survivors and rescue them. Tigris was despatched from Bombay and Isabella from Sydney in 1836.
See the story of the survivors of the Charles Eaton on my website, under Galleries - The Last Fleet series.
http://www.gaylereicheltart.com/