Can a hermit die due to not having available space in his shell?

Question
One of my hermit crabs died after a year, he was laying in his water with no movement what so ever and when I picked him up he was limp and began to slip out of his shell until he only hung from his abdomen. We give the crabs both fresh and salt water, we give them a variety of food (and a good supply of regular hermit crab pellets and calcium). They had plenty of space to roam and enough sand for them to comfortably molt. The humid environment we provided was fairly well because the crabs were chirping and were very active (we made sure it wasn't too humid as well). After being sure that our crab was 100% dead and not just molting I extracted him out of his shell to find that his abdomen was about 3-4 inches long! He was only about an inch and a half big (or so I thought), and didnt expect for his abdomen to look so abnormal. small veins were protruding and it was hard to extract from the shell. I did some research and was not aware that they had to have specific shells to comfortably move into. We provided random shapes that now that I look at them, are not very good for them (some cannot retain moisture, entrances far to wide etc.). I also remember him sleeping while being exposed rather than hidden in his shell like the others. Is it possible that my hermit crab died due to extreme discomfort? Since we got him last June he had only molted once during November. I am planning on purchasing a better variety of shells (another of my crabs does not sleep in his shell, he is always exposed) in hopes to avoid this issue. Thank you for your time, you must get tiresome from responding to the same "is it dead or molting" questions (:
-Christine

Answer
A crab will not die due to discomfort but a crab who is stressed is more susceptible to stress and illness. Additionally, the abdomens are soft and need to stay moist and an inadequate shell might squeeze them, not keep their abdomens moist, or simply stress them out.

They do have very long abdomens, wrapping through the spiral of the shell often one and a half times around. It's really extraordinary!