Complex sentence: Several of Burden's other performance pieces were considered somewhat controversial at the time: another "danger piece" was "Doomed", in which Burden lay motionless in a museum gallery under a slanted sheet of glass, with a clock running nearby.
Split into simpler sentences: Several of Burden's performance pieces were considered somewhat controversial at the time. Another such "danger piece" was "Doomed", in which Burden lay motionless in a museum gallery under a slanted sheet of glass, with a clock running nearby.