What is "cambrothyra"

Cambrothyra (not to be confused with Cambrorhytium) is a Lower Cambrian coeloscleritophoran from China. The fossils are hollow cones with porous walls that had an originally fibrous aragonitic mineralogy. These conical sclerites were generally not connected to other sclerites; only occasionally are they paired or twinned. The genus comprises the sole species C. ampulliformis.