How To Get Rid Of Rocks In Gal Bladdernatural How Did Snails Get Into My Aquarium? (pls Read The Entire Question)?

How did snails get into my aquarium? (pls read the entire question)? - how to get rid of rocks in gal bladdernatural

I'm confused! While I was feeding my fish today, I happened to glance into the substrate, and noticed a snail shell (trumpet). I thought, "What on earth happened?" It is 1 inch long. Then I realized that moving the damn There! Was there a snail ... then to the warehouse and found more than 3 Trumpet snails crawling on the floor of the tank.

Some info (and I'm confused):
- I had made room for more than 2 years.
- It is a community of African cichlids 55 gal (warm'ish water, increasing pH, etc.).
- I have not introduced new products into the tank, since the original game (in addition to changing the water), with the city tap water, and pieces of the new filter. I have rocks and artificial plants twice alast year to give them some cleaning down. The tank is very clean and healthy, in other words.
- Has no living plants in the tank, nor have I had live plants in this basin. ... Not that the natural plants are bad, I am just saying this b / c of the worm eggs, usually in a tank are introduced by aquatic plants.
- During the initial setup has the rocks and the substrate is thoroughly cleaned, so there is no pollution in the reservoir.

I have done nothing different in this reservoir during the past 2 years. No new chemicals or plants or fish is new, no new substrate, etc.

Where do these little suckers? The sky falls? lol

I know how to get rid of if I want, do not worry do not be afraid to usefor it. I just want to know where they come from! I'm confused!