I bought 5 baby assassin snails 3 weeks ago. He sent 10 to account for any that may not make it during shipment. They were very tiny. About the size of a sesame seed and 10 total. I saw them crawl away and I haven't seen them since. Is this normal? How long will it take for them to come out if even alive? Meanwhile I'm getting over run by pond snails. The one time I think I saw one of them was when I introduced my mystery snail. A tiny snail came out and started chasing him around and then lost interest. Is there a rest in can do? This is a 10 gallon plantef betta tank with mopani and no artificials .