It can die but it would take a tank crash or being exposed to air and/or freshwater for a length of time for it to die. The rock is basically just a place to house "live" nitrifying bacteria so if your concerned it may be dying, watch your water parameters. Spikes in ammonia and nitrite are an indication you have some die off. If you are referring to the "live" part as critters living on the rock dying, you'll still see spikes in your parameters as well you may see some white film covering the rock. That would be from dying sponges and such.