So much so that they decided to add their own contribution. They didn't have the time (nor the strength!) to build their very own pillar but they could place some smaller pebbles on the pillars which were already there.
They were all very pleased that they had managed to be involved in such a wonderful spectacle and will make sure that when they visit again, they will try to find their particular pebble pillars and maybe add some more pebbles too.
Maybe if you ever travel to Moelfre, you can see if you can find the hidden beach with the pebble pillars - it really is a sight to behold!