I'm trying to unlock this but I can't seem to understand the part where it is said destroying marked objects because I don't even know what are the marked objects!!!!!........Please help me!

the marked objects are the boxes,barrels and chests ..,..you need to start at entry woods and start smashing all of those until the end of the forest(fire fortress)..note*.=dont go back to and area where you already smashed all objects.just continue from the start to the end(means no going back!)= i got myself messed up in thiss one too until i discovered out..