What's eating my Echinacea

Meomye

I recently purchased two different, young, Echinaceas which are romping away quite nicely but something has taken a liking to one of them and is munching on the leaves. I just wondered if there was any particular critter that likes Echinacea? and find it odd that it doesn't touch the other one as they are sitting next to one another in pots. 

Fire

A picture would help to tell

Lyn

Slugs will have them to the ground overnight. Look underneath the pots you may see him.