Function of inflexible ‘roots’ of Palaeozoic crinoids and solitary corals

Although not a common feature of either group, solitary rugose corals and Palaeozoic crinoids may be anchored by unsegmented, rod-like root structures, referred to as ‘radiciform’ processes and ‘pseudoradices’, respectively. Crinoid pseudoradices likely penetrated the sediment radially from the column, like the roots of a tree. Radiciform processes may have fulfilled a similar function for a solitary rugose coral, but they were also encrusters.