friend or foe?

[rikkuzx]

hello all, have some enquires here. i have this particular snail (i have attach the photo below) which i believe is a hitchhiker from the liverock. it has doing a good job in cleaning my tank off diatoms and whatever algae from the glass (i know this because my tank only start to be crystal clear after this snail start to increase their population). i would like to ask whether this snail will pose any risk if their population keep increasing? currently i have more than 10 of them in my tank now. thanks.

[yikai]

friend

[vipermako]

hi, can give me 1 or 2 to populate my tank. start to hv diatom liao:-)