Some researchers believe that Dactyl formed from debris blown off from Ida because of cratering , while others suggest that Ida and Dactyl formed as a pair a billion or more years ago when Ida 's parent body was disrupted . Dactyl may have originated at the same time as Ida , from the disruption of the Koronis parent body . However , it may have formed more recently , perhaps as ejecta from a large impact on Ida .