HCA: Hermit Crab Association

I'm really new to taking care of crabs. I got one (his name's Helix) near the end of my freshman year in college from my biology class and had no idea how to take care of him. I got online and learned about the conditions he'd need, but I didn't have a lot of room in my dorm so the poor guy had to stay in a critter carrier. When I got home I bought a ten gallon tank and got it all set up for him with lots of sand and shells and things to climb on and a new friend (this was in early May). The new guy (Dome) is quite a bit smaller than Helix but after their initial meeting (where Helix flipped Dome over and checked him out) they got along fine and everything was going well. About a week after I put Dome in the tank they both disappeared under the sand. I've read a lot of other discussions on here about new hermies burying themselves for a destressing period so I left them alone. I put in fresh food and water every night and kept the temperature and humidity in a good range. However, it's been a little over a month now, neither of them have come back up, and I'm starting to get worried. I don't think either one is dead because it doesn't smell like there's something dead in there and every now and then I'd hear one of them digging (although it's been a few days since I heard any). I don't know if either one was ready to molt because they didn't seem to be eating a whole lot and I didn't see a sac or anything (although I hadn't handle either one much that week because I wanted them to get used to their new home without me scaring them). So hopefully you guys can help me, because I don't know what to do. My dad thinks I should dig them up, but I don't want to bother or possibly hurt them. Does anyone have any suggestions?

Two suggestions1- if you can look underneath the tank without causing risk, look to see if you can see either of them, often they will dig all the way to the bottom. It might reassure you that everything is fine.2- I would leave them alone for at least another month before assuming they have died and digging. If they are dead, another month won't matter, if they are molting, disturbing them now could be a life threatening thing.I had a tiny one who now molts for about two weeks at a time. When she was brand new, she went down for so long I was sure she hadn't made it. It was months! Fortunately I was being very careful in my excavating, just in case, because she was alive. The bigger they are the longer they usually molt. The ones. I have had for a few years who are approaching the size of a ping pong ball molt for about 6 weeks, up to that point they would be closer to 4 weeks. After three months the one with a shell opening smaller than a dime, really closer to a pea than a dime, I expected to have died, as I said above, she fooled me! It is hard to wait not knowing.Also note that you won't necessarily smell anything, especially if they are buried.

OK. Thank you! I don't think I can look under the tank so I'll just wait out another month.

When I first got mine they were down for a good 2 months before coming up.