Underground for Months Yet No Molt

[Lilyco]

I have two hermit crabs named Romulus and Remus, and after a series of events over the past months I don't have time to explain Romulus is in a critter carrier separated from Remus. Back in January I tried re-introducing them to each other and Romulus buried himself almost instantly. I shrugged it off as him molting but was annoyed I wouldn't be able to deep clean the tank. A month later I took out the wood due to mold and there he is. No changes to his exoskeleton though. I move him back into the carrier to see if anything happens and he buries himself. In the meantime I deep cleaned the tank. Today, two weeks later, I finally see him active and moving but still no changes to his exoskeleton. Not hairy, not darker, nothing showing he molted. Thought about it for a while and decided to share this story for any ideas the wonderful people have as to what is going on. I think it may be stress, but he was buried for over a month and only the past few days have I been seeing changes in the topography and this afternoon I saw him on the surface. He also hasn't molted since September 2020 and is a medium PP so in my opinion he is overdue for a molt.

[curlysister]

Why do you keep moving him back and forth? There is no need to move a crab to isolation molt, it is better to leave them in the main tank.
What are you using for substrate? How deep is it?
How big is your main tank?

[Lilyco]

Why do you keep moving him back and forth? There is no need to move a crab to isolation molt, it is better to leave them in the main tank.
What are you using for substrate? How deep is it?
How big is your main tank?

I thought it might be safe to move him into the carrier if it was a molt since the last time I had a molter surface with a cage mate on the surface it ended in a fight. However, I now realize that assuming he was molting wasn't exactly a smart assumption since there was little evidence he was. The substrate was a mix of eco earth and sand but I didn't measure how much I was using. The substrate after deep cleaning is about 3 parts eco earth and 1 part sand. The deep clean also happened because not only was the tank smelly but the substrate was damper than ever and I couldn't pick through and find any poop or food I missed when spot cleaning so I moved them out to clean the tank. Romulus buried himself in the carrier though and I didn't want to dig him up so I put the carrier in after cleaning. I am not putting the carrier back into the tank or moving them now that they are reunited in the tank. The substrate is five inches deep in the main tank and the main tank is 30 feet long, 12 feet wide, 12 feet tall. It is Aqueon's 20 gallon long and large enough for the two of them. I'm not going to be moving them again until the tank eventually needs to be deep cleaned.

[wodesorel]

They don't always change appearance after a molt. Also, crabs will stay down for a long period before and after actually shedding, to where they look completely normal but are actually in a weakened state and not capable of safe above-ground activity yet.

That they're wanting to be buried and are staying down so long is a good sign. I'm betting they did sneak off a molt and just didn't change appearance enough that it became noticeable.