Cylindracanthus rectus was a rostrum-bearing ray-finned fish whose systematic position remains unresolved. It is known primarily from long, dense rostral fragments with a characteristic internal canal system. The specialised bill shows that the animal had a strongly modified snout, but without securely associated skull and body material it is unsafe to reconstruct it as a particular modern type of billfish.

Its ecology is consequently inferred only in broad terms. A projecting, reinforced rostrum is compatible with an active marine fish and may have been involved in prey capture or sensory functions, but the exact use remains unknown. The taxon is an important reminder that similar rostral structures evolved in several unrelated teleost lineages.