Filter Snails.

[Hermithall]

Just noticed some malaysian trumpet snails inside my external Eheim, just kicking about all casual and having a merry time. I don't mind MTS in my tanks because the benefits seem to outweigh the downsides, but I'm not sure what to make of this. It's not something I've noticed before - snails in an external filter, but I can't say I'm totally surprised that they've made it all the way down there. I'm wondering if anyone else has this 'problem' and if there's any potentially serious consequences?