THomas Welsby states in his Recollections of the Natives of Moreton Bay. Together with some of their names and Customs of Living delivered before the University Historical Society in 1967 that
"At that time, i.e., about 1879, there were many natives at Amity, some of the real dark old-day men, and as the moon was at its full, an improvised cor- roboree was given by the men and their gins. One comical native—and one, I daresay, well remembered by many boating men—was living there at the time, his gunyah being very close to tlie beach, not far from where the present test-house stands. He liad a deformed arm and leg, and could not take part in the more active games and dances of his comrades. He was a born actor and a wonderfully clever mimic, and as cunning as the verit- able rat. His name was Cassim, or, as he himself would ever put it, John William Cassim, Esquire. He was not the Cassim who kept the hotel at Cleveland'. (p.115)
"Billy Cassim, who sang a fairly decent song, English and black words intermingled, as he deemed it necessary,, was also the author of many Amity Point corroborees. His native name was "Nyoryo" supposed to mean "ropehauler." How often have I heard him sing, "We won't go home till morning," and "Rule Britannia." It hasbeen said that Billy was the composer of two comedies, "The Chinaman Corroboree" and "The South Passage Corroboree." (p.116)
"Billy Cassim died in 1890, and lies asleep not far from his namesake, Cassim of Cleveland, the burial being made in the native quarter in the Dunwich cemetery," (p.117)
An Indian national Johnny Cassim was transported to the Island of Mauritius for the term of his natural life in 1828. After transport again to Moreton Bay hee obtained a Ticket of Leave in 1843, Cassim went onto own boarding houses and died in Cleveland in 1884 a property owner and respected business man.
An Aboriginal man John William Cassim Esquire (Billy) was one of the men who rescued survivors of the Sovereign in 1844. It is assumed he took his name after 1855 when Johnny Cassim came into contact with local people. Patrick J Tynan in his book Johnny Cassim Coolie - Convict - Catchumen - Colonial Entrepereur 1814-1884 suggest that Billy Cassim would have "taken on Cassims' name" as "It often happened that Aboriginal people took the name of one of the non-aboriginal arrivals in their area, out of admiration" p.71.
Cassim Island was named after one or perhaps the other of these gentleman.
Of the Cassim Island wreck A. J. Pixley in a 1970 reading Shipwrecks ev Queensland and Adjacent Waters to The Society says
"At the time I thought it may have belonged to the steamer Toondah, the remains of which ship lie on Cassim Island just off Cleveland. This is the ship in which Cecil Fison's grandfather surveyed and beaconed the channels of Moreton Bay. My assumption that this boiler came from the Toondah proved to be wrong. CecU Fison told me that the boiler and engine had been removed at the Port Office. How or why the hull finished up at Cassim Island I am unable to say". (p.154)
Image taken from Tynan, P. J. (2005). Johnny Cassim Coolie - Convict - Catchumen - Colonial Entrepeneur 1814-1884
https://www.youtube.com/watch?v=dnki-t9cIY4 Retrieved June 15, 2017
Pixley, A. J. (1970) iShipwrecks ev Queensland and Adjacent Waters. Reading to The Society.
Tynan, P. J. (2005). Johnny Cassim Coolie - Convict - Catchumen - Colonial Entrepeneur 1814-1884. Church Archivist's Press.
Welsby, T. H. O. S. (1917). Recollections of the natives of Moreton Bay. Historical Society of Queensland Journal, 1, 110-129.