water perameters are all fine and my temp is at 70 degress. my 3 gold inca mystery snails have been in the same spot for the last couple of days and sit there all day with their door open a little crack. when i touch them they slowly close up into their shells again. they are about 2 weeks new into my tank but were very active the first couple of days and then just kind of went dormant. why are they doing this? are they just dying?