HMAS
Cerberus, Ocean Going Monitor, which is looses terms still exists.
Commissioned in 1871, she was part Queen Victoria's efforts to shore up the British Colonies naval defenses.
The
Cerberus was armed with 4 (in two turrets) 10 Inch (18 tons) guns,2 6-pound guns, mix of Gatling guns (I've never head these being on ships before) 1 inch guns to round up it's weapons. She was later made into ammunition store ship in her last years.
She had a quiet life until she was decommissioned and made into a breakwater at Black Water Reef for the yacht club. She there still, however she is sinking more into the sea bed. There grass roots efforts try rescue her, but i don't think they've been successful.