I used a live lobster, which I purchased at the local supermarket (we live right across that Consum in Valencia, and there are live lobsters there, in spite of being such a basic supermarket...), named Thermidor (in an unsurprising display of black humour), and kept as a pet for twenty minutes or half an hour, until the water boiled.
Half an hour of eviscerating the lobster shell and claws (keeping the flesh and putting it back in, of course!) and making béchamel and thermidor sauce (the latter comprised of two glasses of the fumet our lobster and a cube of Knorr fish stock were boiled in, with cream, brandy, Chardonnay, Dijon mustard, and parsley), and five minutes of oven-gratin plus five more of cooling, later, the dish turned actually scrumptious for a beginner.
Nowadays (as of the date this post was published) all that remains, for a keepsake, is a block of frozen thermidor sauce in our freezer, with a handwritten label on it that says:
sauce for seafood
So that we don't forget what that block of pale mustard-yellow ice with chunks of parsley is, as well as what to be served with it.
Someday pretty soon, there will be prawns thermidor for supper, to finish off what was left after the lobster shell was emptied by us.