Complex sentence: Although the family is known only from larval, paralarval, and juvenile specimens, some authorities believe the adult creature have also been seen; several videos have been taken of animals nicknamed the "long-arm squid", which appear to have a similar morphology.
Split into simpler sentences: Although the family is known only from larval, paralarval, and juvenile specimens, some authorities believe adult specimens have also been seen. Several videos have been taken of animals nicknamed the "long-arm squid", which appear to have a similar morphology.