Article: Significance of coiled protocoralla in some Mississippian horn corals

Planispirally coiled protocoralla are described in Cyathaxonia tantilla (Miller) from the Lower Missis-sippian (Lower Carboniferous) of the western United States, the first record of this phenomenon in corals. Coiling is interpreted as a mode of attachment of young coralla to planktonic algae. The postulated pseudoplanktonic growth habit may be a significant factor in the widespread distribution of this species and other species of Cyathaxonia, which are generally found in rocks that record a bottom environment considered unfavourable for optimum coral growth.