A slice of fatberg put on show at the Museum of London could be preserved for future generations.
The lump of congealed fat, oil and wet wipes has begun to "sweat" and change colour - and flies have hatched in it.
But curator Vyki Sparkes says the fatberg caused a "marked increase" in visitors to the museum and they are now thinking of preserving it, when it finishes its public display this week.
There has been an "incredible reaction" from visitors, she says.
It has become one the museum's most popular exhibits, says the curator.
The piece of fatberg was taken from a "monster fatberg", over 250m (820ft) long and weighing 130 tonnes, which had become something of a sewer celebrity, when it was found under the streets of Whitechapel.
Fatbergs are an accumulation of materials flushed into the sewers that form huge solid blocks - with the Whitechapel fatberg taking nine weeks to break up with drills.
In the first such exhibition of its kind, the Museum of London put this slice of urban history on public view in February, as an example of the challenges of getting rid of waste in the capital.
The display ends at the weekend, but Ms Sparkes says they have been taken aback by its appeal, with people making special trips to see the fatberg and boosting visitor numbers.
There has been a mixture of fascination and revulsion, she says, not least to see how the item has changed, under its glass case.
"We've never worked on anything like it," she says. There is an element of "mystery" about it, says the curator.
"It's under our feet, it grows. We're all responsible for creating it."
The museum is now considering whether to keep it in its archive, rather than throwing it away.
The rest of the monster fatberg has already been chopped up and converted into bio-diesel.
In the short term, the fatberg will go into "quarantine", where it will be treated with the type of health and safety regulations surrounding sewage.
Next month the collections committee at the museum will decide whether the fatberg will be kept forever as an artefact, either in storage or on display, rather than being returned to the rubbish.
Ms Sparkes says she now has a "big soft spot" for the fatberg and says there is a "strong case for keeping it".
Even if people have thought it was revolting, she says they have engaged with the ideas behind it - such as the consumer behaviour and type of consumption that creates fatbergs.
The museum's curator says there have even been artistic responses to the fatberg - with children's stories having been written.
There is even a fatberg musical - currently in the pipeline.