Why is buckminsterfullerene an allotrope of carbon

Buckminsterfullerence is called an allotrope of carbon because it was discovered during an experiment involving a cluster of beam which uses laser to vapourise  a graphite rod in a helium atmosphere to produce carbon plasmas.a mass sectrometry evidence from the experiment showed that carbon molecules with C60 were forming with a spheroidal geometry.so therefore it was included as an allotrope of carbon.