I shipped corals to friends in NV and in FL.
I put some in plastic bags, some in a thermos, and some in cheap temporary wanna-be Tupperware containers.
These I packed into styrofoam with heat packs (hand warmers).
The stuff in the wanna-be-Tupperware didn't make it. The lids popped open and the water leaked out. The Thermos was the best method.
If I was going to do it again, I'd save some clean small glass jars and screw the lids on tightly.