My hermit crab has buried himself in his shell grit?

Is it normal for them to bury themselves? I only got him today.
Answers:
Yes it is destressing leave it alone. And here is a great caresheet to help you with your new pet
Housing/Crabitat:
no smaller than a 10 gallon glass tank, is preferable. A glass or plexiglass lid is also preferable, to keep proper temperature and humidity.
Temperature: 74-78 degrees F (thermometer)
Humidity: 70-80% relative (hygrometer)
Substrate:
Playsand, Forestbedding (Eco-Earth, Bed-a-Beast, etc). Moss and calcisand may also be added to the tank, however it is not recommended as a main substrate.
Diet:
Commercial crab foods, Vegetables (favorites include-carrots, lettuce, parsley, spinach, and corn), Fruits (favorites include-coconut, mango, apples, grapes, and pears), Meats (seafood, silversides and chicken are favorites), Grains, Peanut butter, eggs, seeds, algae and seaveggies. Please see http://www.epicureanhermit.com for a list of other edible foods.
Purple pinchers need both fresh and salt water (dechlorinated %26 salt made with a good marine salt like Oceanic).
Shells:
Turbo, pica/magpie, Sharks eye. Shells with circular openings are favorites
Molting:
-Lethargic before and hyper after molting
-Legs tend to be dry and ashy pre-molt
-Will sometimes molt without a molt sac or other pre-molting symptoms
-Are thirsty and hungry pre-molt and post-molt
Other Characteristics:
-Sweet/nice temperament
-Love to climb
-Love to crowd into piles
-Not as active as other species such as the Es
-Like to hide during the day and are most active at night
-More willing to pinch if they feel threatened/scared
-Love to change shells
-Love to eat and climb on wood such as cholla/choya and corkbark

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i had a hermit crab once.
but that never happend to him/she
(i had no clue what gender it was)
go online
to see if thats normal