An old sign painted on a brick wall could be the latest item on Heritage Victoria's register if a local politician has his way.
But it's not just any inscription on any old wall.
It has been a feature of a novel and film and the title of a Melbourne artist's exhibition at the Venice Biennale.
It has come to symbolise a community struggle that is now used as a model in academic studies of grassroots political action.
Its origins have been debated by historians and locals alike.
It has been leant against, sunbaked and splashed on.
It's the AQUA PROFONDA sign at the Fitzroy Pool, and if Victorian MP Richard Wynne is successful in his application, it will be preserved for all time.
Mr Wynne, member for Richmond, lodged the application with Heritage Victoria last week. He believes the sign is an important testament to the history of inner-city Melbourne.
In his application, Mr Wynne said the sign and wall had statewide and national cultural significance due to its appearance in Helen Garner's 1977 novel Monkey Grip and the subsequent film of the same name, in which its translation "deep water" became a famous metaphor.
Mr Wynne said the sign, believed to have been painted in the 1940s or 1950s, also symbolised the migrant history of the inner city.
The move to have it placed on the heritage register has been applauded by the Friends of the Fitzroy Pool - a group established in 1994 when a new council threatened to close the almost century-old pool.
Then, the words Aqua Profonda became synonymous with the fight to save the pool, which has legendary status among locals, and ended up being the title of a play about the struggle performed by local primary schoolchildren. The play was written by Melbourne playwright Hannie Rayson.
Heritage Victoria executive director Ray Tonkin said he had received Mr Wynne's application, but could not say what chance the sign had of being listed.
He said a decision was likely in about three months.
While it is an unusual application, it is not without precedent. "We do have advertising signs on the register," Mr Tonkin said. "We're currently looking at the Nylex sign in Richmond, and the Pelaco sign (also in Richmond) is on the register."