Fig. 8
Thin-section photographs of Girvanella and Ortonella. a Girvanella boundstone with micritic texture colonized by tubular thalli (white arrow) and the clotted micrite (black arrow); b Girvanella-like organisms bore shell: the thalli in the shell (black arrow) and encrusting the shell (white arrow); c Transection of Ortonella: tubes were filled of microsparry or sparry calcite (white arrow); d Longitudinal section of Ortonella, showing closely-packet tubes (white arrow)