The Vhnori world is the site of many naturally-occurring subspace vacuoles, and these form the core of the Vhnori death tradition. They originally placed the bodies of the dead into these vacuoles believing that this would transport them to the Vhnori afterlife, called the Next Emanation.
Unknown to the Vhnori, the vacuoles actually led to a planet in the Delta Quadrant. On this planet, the bodies of their dead had been piling up for thousands of years, resulting in the only known concentration of the 247th element.
All this was accidentally discovered by Harry Kim of the USS Voyager when he was accidentally drawn through one of the vacuoles to the Vhnori homeworld in 2371. He returned using one of the cenotaphs, having seriously disturbed the Vhnori's faith. However, it was discovered that an unusual amount of neural energy existed in the planet's rings, perhaps implying that the Vhnori afterlife may not be completely without foundation. (VOY: "Emanations")