Buying sponges online is a bad deal if you ask me.As the air thing may take awhile to show up.And as said in previous posts,you never know how it was handled during shipping. The air kills them by cutting off thier ability to filter feed. They have millions of tube like pores on thier surface that filter the water by syphoning it into these tubes. If an air bubble gets into this tube it blocks,or stops this syphon.and the sponge basically starves.