i have one in my aquarium and i dont see a problem with the fish eating/picking them unless there is food stuck to them.I don't know why the ones you saw were floating as the ones i bought sink
yea when i look at pics online...i only see them sinking. this was the first time i have ever seen them in real life and there was about 8....all floating
Maybe the store didn't squeeze the air out of them. They should sink with no problem. Even when mine are pearling they stay down. Part of regular maintenance is to give 'em a good few squeezings at water changes to help maintain a round shape and get some of the dirt out of 'em.
we saw a couple at the store that were floating, they had them tied with fishing string to a sinker so it looked like they were floating in mid air. ours doesn't float, it gets caught in little currents sometimes. and the swordtail shouldn't bother it, we have a couple platys who eat algae and they don't eat it, they pick stuff out of it though.