Check the store for CAVE BACKGROUND. Or maybe you need to do some research how to get this item. CAVE BACKGROUND is in background tiles category. CAVE BACKGROUND gives experience points when broken. CAVE BACKGROUND can be broken. Seed mathematics is very complicated, but you should get at least 1 seed back from splicing CAVE BACKGROUND. Profiting with this might be questionable. Will you get enough blocks to build something? You just have to find out yourself.