<prompt> Surfers ear differs from Osteoma in that it is :UnilateralSingleSessileSeen in cailaginous canal  <response>: Exostosis is bilateral multiple smooth sessile bony swellings in the deeper canal seen in diversswimmersSurfers. It is called Surfers ear. Osteoma ExostosisSurfers Ear Single Multiple Unilateral Bilateral Pedunculated, hard Sessile, smooth Outer canal Inner, deeper canal 