Can someone explain this? I have several astrea snails in my 75g tank. I also have two power heads on either end with the cords going straight out and over the back of the tank. The snails love to congregate around and under the cords. Right now, there are six snails crowded around the cords. I wouldn't care except that the pressure they put on the cords makes the power heads vibrate against the glass. It's very annoying. Just wondering if anyone has seen or heard of this behavior before.