they're in a plastic container & I wondered about the freezing because I freeze plain prawns in their shell or peeled ones but i've not had the ones in liquid before. They are in a container similar to the hummus/coleslaw containers where you have to break a tiny seal to open the lid.
By rights it should say on the front 'suitable for home freezing' - if it doesn't, I think you can safely say they've already been frozen, and the brine on them is thawed liquid
It hurts the texture some to refreeze them but the important thing is to freeze them quickly(as in as cold as you can get your freezer). Otherwise boil what you don't use today for cocktail and freeze.