Recently I baffled Tango's filter with an Aquaclear sponge. I had some pieces left over and I notice they float so I put them in the corner of his tank so he could use them for bubblenests. Today I put two IALs in his tank and I didn't want them to sink. I wanted him to use them for cover at the top so I draped them over the floating sponge which also has some wisteria stuck to it. Viola! He's got a little tent to hide under with greenery to rest in. He's seriously LOVING it.