HCA: Hermit Crab Association

Well, just about 4 days ago i bought 2 purple pinchers. I got a 10 gallon tank with some sand. I have a water bowl with a sea sponge, and a little hideout spot. Well, my crabs either hide under it, or go to the nearest corner and do not move AT ALL. What is going on? Are they de-stressing?

They are also in unpainted shells. I'm also sort of new to this :/

Get used to it! They probably are de-stressing to an extent, by they will naturally have frequent, sometimes long, periods of not doing a whole lot. They will also get active too though. If you provide things to climb on and explore they will check them out. Also, make sure your temps and humidity are good, and as consistent as possible. If they're cold or dry they will certainly hide. But they are inactive pretty often, I have 10 of them in a 55 gallon tank and the most I've ever seen at one time is 5! When you're a hermit crab every day is Sunday.

How deep is your sand? What type of sand are you using? What are your temp and humidity levels? Hermit crabs need dishes of both salt and fresh water deep enough for them to fully submerge in. Salt water is mixed using an ocean water mix from the fish department in a pet store. Popular brand are Instant ocean and Oceanic. Salt water sold at pet stores labeled for hermit crabs should not be used for hermit crabs. It is most likely salt mixed with water(BAD!).
Edit: Sponges are a breeding ground for bacteria, most people on here do not recommend using them at all.

They are likely destressing. It's best to just keep your temperature and humidity close to 80/80 and leave them alone for week or so after you get them to give them some time to adjust.

The hermit crab salt is normally sea salt and water. While it won't hurt them, it also isn't everything they need. The marine salt mixes will provide all the needed minerals.

Heat and Humidity help in activity level and access to climbing items such as cholla wood and mopani.Sponges only can produce bacteria if left in the water or substrate for long periods. Sponge put in dry or used in a caddy makes for a good nesting spot. Crabs love to eat sponge it provides good nutrients.I have been using a sponge pit for 2 years and no bacteria or smells.Crabs love it.
IBlab crab