Fireplace envy

A friend from French classes has just bought a house nearby, so a few of us went over for coffee and a look round. They have a beautiful fireplace with a heart on it, which is similar to my fireplaces but I don't have symbols on mine!
Apparently the symbols have meanings so it would be interesting to find out more about them. It's a lovely house and also has a stone potting shed....... I really need a potting shed (a stone one would be nice)