In prison for a pebble
Don't move it around — too much
South Africa has a broad range of regulations governing how visitors may enjoy its public beaches. Fishing, open fires, bringing dogs: there are detailed rules for everything. It's forbidden to remove rocks or sand from the beaches as well as to "excavate, or tunnel in the sand or cause any substantial movement of sand." But, "reasonable digging of holes by children or beachgoers" is OK, though.