In Superspins, symbols involved in the win are locked in place and can therefore extend your success.
Superspins
Superspins are, similar to free spins or Wild symbols, a fixed component of some game systems. They are triggered by a success. You will only encounter Superspins in selected games – two well-known examples are Achilla or Zentaurus . In Zentaurus, for example, Superspins are only awarded during the free spins. During the Superspins, symbols that were previously involved in the achieved win are held and an additional free spin is granted. This repeats until no further symbols land to extend the payline.