When I had my crays shipped to me, they were pretty much adults. She shipped them in a regional box (which are the smaller and more box-like instead of rectangle boxes the usps sells) in breather bags. Two were in the same bag and one by itself. Some insulation and newspaper. They all made it. Even the two in the same bag were fine, even though IDK if I would actually recommend putting two in the same. So yeah, in my experience they were shipped the same as fish or shrimp.
Of course the LFS would be much easier.
Of course the LFS would be much easier.