Welcome to Healing Well.
.5cm definitely isn't the same size as a quail egg, but my FIL had one the size of a buckeye they had to do the "sonic blasting" on, forget the name right now.
My largest was 10mm or about 3/8ths inch. They went in a broke mine up and retrieved the pieces.
Moderator: GERD/Heartburn, Kidney disease
Esophagus tear 02/11
Nissen 6/06 and 5/09