Whilst visiting the Allied War Cemetery of Souda I noticed that quite a few gravestones had snails on them, nestling in the carvings.
In this particular gravestone they have chosen to congregate in the emblem of the RAF. Per ardua ad astra ("Through adversity to the Stars") is the motto of the Royal Air Force and other Commonwealth air forces such as the RAAF, RNZAF, and the former RCAF. It dates from 1912 and was used by the newly-formed Royal Flying Corps.