Bergstrom (1972) reinterpreted the limbs of Cryptolithus, concluding: "The exite ‘filaments’ of Cryptolithus evidently are strong spines that pointed ventrally and may have been used to stir up deposited mud.
The broadened view of trilobite appendages indicates that some trace fossils (Cruziana semi-plicata type) may be interpreted as being partly made by the exites, while others (C. rugosa type) are perhaps made exclusively by the exites."