Hello and thank you for your message.
Generally the best way to get rid of the xenia is to use a wood chisel and slice the xenia off the rock they are on. You just want to remove a thin layer of rock beneath the xenia to remove it from the rock.
If you do a google search of "fragging xenia" it will bring up lots of great ways to do this along with multiple videos.
If there is anything else we can do for you please let us know.
Marine Depot Customer Service