A new species of Mucophyllum rugose coral encrusted by bryozoans, tentaculoid tubeworms, and tabulates from the upper Silurian of Saaremaa, Estonia

Mucophyllum toomae Kazantseva sp. nov. is characterized by a large broad calice with a small flat floor, numerous thick septa, and lack of dissepiments. An unusual type of syn vivo symbiosis and post mortem encrusting was found on the holotype. Tabulates are represented by small colonies of Aulopora sp., encrusting the frontal surface of the specimen, including the coral cup and partially observed in a sediment in its central part. Stenolaemate bryozoans include a discoidal expanding cystoporate ?Ceramopora sp., a sheet-like cystoporate ?Fistulipora sp., and a dome-shaped trepostome ?Eostenopora sp. Two of the bryozoans, ?Fistulipora sp. and ?Eostenopora sp., were found on the frontal surface of M. toomae, while the third bryozoan, ?Ceramopora sp., encrusted its lateral surface. Presumably, the lateral surface of the coral could have been encrusted syn vivo, whereas its frontal surface has most likely been colonized by bryozoans post mortem. This conclusion is supported by the presence on the bottom side of the calice of ?Anticalyptraea, which seems to have an attachment scar.