Captain Hammer and Thor are dead - why?

[beepboop]

They have both been in the same places for days. I could see Thor had lost both claws and a couple legs, so I was sure he wouldn't live because I've had them only two weeks. The tank smells fishy, it's really strong, and when I picked up Captain Hammer by his shell (he wasn't buried, just in the same place for days), there were limbs under him and a leg dropped out of his shell. The same thing with Thor.
Was it PPS?
Panic!, by the way, is fine.
Just so you can help me figure out what killed them, here;
EE substrate
Instant Ocean Salt
API Tap Water Conditioner
75% humidity 72 degrees in the tank (a bit low, I know.)

[CrabbyJo]

72 over a long period is far too cold. Without a warmer place to move to, they could not regulate their body temperature, I'm sorry to say. They really do need a temperature range - cooler at one end (and in that case 72 is fine) but much warmer at the other end - closer to 80.

[beepboop]

I do have a heat lamp, but I will have to get another thermometer. It raised the temperature from 60 to 75 the one time I used it (when the house was realllly cold due to technical difficulties)
I guess I'll set it up tomorrow in the morning. I'm going out of town this weekend and my friend is taking care of the pets so... (she's feeding them from baggies I prepared and put in the fridge for each day.)
It wasn't exactly a long period of time, I don't think. A bit over 2 weeks.
Plus, Panic! is just fine. He's smaller, though. My theory is PPS. I think that since larger hermit crabs are older, they get more used to being in the wild while the younger ones are able to cope better because they haven't been in the wild as long. Captain Hammer was quite large, and Thor not far behind, while Panic! is pretty small. Would being too cold cause them to drop both claws and two legs, then die maybe 2 days later?

[ladybug15057]

I am sorry to hear they have passed, but there was a posting with replies regarding the surface molting and the questions you answered:

viewtopic.php?f=24&t=4028&p=33432#p33432