On walking through the front entrance of Fairlop Waters, its recent addition – a musical sculpture or “singing rock” – is already visible standing on a distant hill.

The art installation Nothing is Set in Stone, which contains hidden sensors and speakers so that it “reacts” to visitors with music, has been in place for three weeks.

The creation of musician Mira Calix, it has been intriguing crowds at the country park off Forest Road, Barkingside, as part of the Mayor of London’s Secrets: Hidden London programme which is backed by Vision Redbridge.

“The egg”, as a member of staff at Fairlop Waters described it, was built up to approximately four metres with thousands of stones with the help of mineralogists from the Natural History Museum.

When the Recorder visited, it was drenched in unseasonable rain, but that hadn’t stopped Sally Sutton, of Norwich, who travelled to see it as a birthday treat for her sister, Katherine, visiting from California.

Escaping the downpour in Fairlop Waters’ bar, Katherine, who heard about it through a friend, said: “It sounded very intriguing.

“I love music, I love stone and I love the outdoors. It seemed a great way to spend a birthday and it was beautiful.”

Her sister said: “It was very lovely, there was a wonderful quality of sound.”

Journeying on to the site, bass notes can be heard from a few feet away before getting up close, the sculpture reveals a series of intricate noises such as stones clicking and birds chirping.

Touching a central stone triggers a burst of energy as the rush of a waterfall seems to run through the stones and at times, it sounds like a berserk jungle.

The incantations of a choir, recorded at the University of Johannesburg by Mira, add a beautiful if otherworldly effect.

Back at the front entrance, the visitors’ book reveals an overwhelmingly positive response to the installation, which will be in place until September.

A sole voice says “what a waste of taxpayers’ money” but other comments include “an amazing work of art” and “it needs a permanent location”.

Catch it while you can.