No the weirdest thing is... never even purchesed any. What happened was (bear in mind im speaking of a freshwater tank) i got some seashells from spain which would presumably be saltwater and all of a sudden a few days later 3 snails, 9 snails and it just escalated. Ive tried getting rid of them, and it seems their numbers increase after water changes rapidly. But in the end i just leave them, i mean they cause no real harm and ive had em for about a year they just clean the algae. But thy are really small, about 5-10mm each but very visible and transparent brown in colour :/