Molting but now naked and completely burried in sand

[golfinfool]

1) How long have you had your crabs and how long have you been caring for this particular crab in distress? I've had 2 crabs for about 2 months, first time molting2) What size is your tank and what kind of lid do you have? 18 gallon tank with screen lid and covered to keep in humidity3) What are you using for heat? Please be specific and include fixture type, watt or mat size and where the heat source is mounted.No heat source, tank stays around 75 degrees4) What kind of substrate do you use in your tank and at what depth? Is it dry or damp and sand castle consistency?sand only and sand castle consistency5) Do you dechlorinate your fresh water and if so, with what product? Do you offer aquarium salt water in addition to fresh water? Again, what product?I use distilled water from store6) What do you normally feed your crabs?fresh fruit and leaves7) Do you bathe, mist or handle your crabs at all?no8) What are the temperature and humidity readings? Please be specific and include high low fluctuations if you're aware of them.temp 75 humidity 83My crab started molting around 3 weeks ago, burried himself under the sand in a tunnel. I checked on him tonight and now he is up and his shell is on top of the sand. he is completely burried in the sand NOT IN TUNNEL. is this a problem, can he suffocate? What should I do?