Snails

[shahdi]

i recently bought a 2nd hand 5 ft tank. with gravel, light, canister filter, heater and some rocks. finnaly i got to clean the tank and fill it up with water to cycle it. i decided to use the gravel that came with the tank. anyway next morning the tank was covered (not fully) with snails. the snails have a cone shaped shell (not like a normal snail). what type of snails are they and will they help the tank or cause problems. is there a way to remove all the snails. the snails arent very big.
thanks