I have two golden apple snails. They're not as action packed as the zebra snails and just seem to remain in their shells
I know one of them isn't dead because it comes out every now and again, but then retreats.
I don't know if the other one is dead. It floated to the top a couple of weeks ago, then sank again. I think it's been out since, but can't be sure 
The tank is well establised, well filtered and my zebra snails are whizzing around as usual.
Are my apples too cold? They were sold to me as cold water creatures. We light the fire in the lounge and it's the warmest room in the house, but we don't use the central heating.