A theoretical black hole formed from highly concentrated radiation rather than ordinary matter is called a kugelblitz.
In general relativity, energy curves spacetime just as mass does. In principle, enough light, heat, or other radiation focused into a sufficiently small region could create an event horizon, trapping the energy inside a black hole. The resulting object would be defined by its energy concentration, not by the collapse of a star or cloud of matter.
The word kugelblitz is German for “ball lightning.” Physicist John Archibald Wheeler used the concept in his 1955 paper “Geons,” which explored self-gravitating concentrations of electromagnetic energy. The term is therefore associated with a theoretical construction, not with an observed astronomical object.
A kugelblitz is often confused with a quasar, pulsar, or magnetar, but those are entirely different phenomena. It is also important that recent theoretical work has questioned whether quantum effects such as vacuum polarization would prevent a realistic light-made black hole from forming. Thus, the quiz answer is a recognized theoretical term, not an established object.