We could hear them walking around in the box. Their feet clicked ominously against the plastic foam. They were dead already, we reasoned. They had been marked for dead since the moment they were born.

But that logic didn’t change anything. The fact remained that there was a box of live lobsters in our living room, and that one of us had to murder them. We hadn’t asked for the lobsters. We hadn’t even expected them. They arrived abruptly, unavoidably, from a relative armed with a mail-order catalog and the best intentions. We had planned to order Mexican food that night, but fate and FedEx had delivered a crushing plateful of introspection instead.

My fiance, David, and I sat on the bed, searching for a way out. Could we give the lobsters to a friend? Donate them to a soup kitchen? Would the creatures survive if we left them in the box overnight and slept on the dilemma?

Maybe we could make this someone else’s problem.

“Do you want a box of lobsters?” we asked friends, flooding the phone lines with affected nonchalance. They all declined.

“Can you keep them as pets?” one offered.

Could we? Would the lobsters live in our bathtub? Would our landlord be okay with that? What do lobsters eat? Can they get bored? Do they need toys? If we set them free, would they rather live in the East River or the Hudson? Or maybe Central Park?

No, the lobsters had to die. The grim prospect seemed inevitable. But who would kill them?

For entirely different reasons, the situation had plunged each of us headfirst in the boiling waters of our individual omnivore’s dilemmas. For me, those lobsters were a living reminder of my gastronomic fall from grace. I was raised as a strict vegetarian but halfway through college had made the choice to start eating fish and poultry. (Not insignificantly, I’m also Jewish, but I can handle only one culinary identity crisis at a time.) At first, the decision to abandon vegetarianism haunted me on a daily basis. The specter of my 12-year-old self followed me into restaurants and grocery stores, munching on seaweed crackers and staring at me with hate in her eyes.

“I’m a murderer,” I once sobbed into my cellphone from a Whole Foods fish aisle.

“Do you need me to come pick you up?” David had wearily replied.

By the time the lobsters showed up, though, those attacks of panic and self-loathing had slowed to a trickle. I’d started to accept my new eating habits — an uneasy peace that was shattered by the arrival of the box.

David’s childhood, on the other hand, was emphatically and aggressively carnivorous. He grew up on a sunflower farm in the rural Midwest, the kind of place where people unapologetically fill their homes and dinner plates with the heads and bodies of dead animals. Dozens of eerily lifelike geese, pheasants, raccoons and deer (many of which 12-year-old David killed himself) peer out from the walls of his childhood home.

So you’d think David would be the obvious choice to off the lobsters.

It’s funny how people change. Something happened over the course of our relationship, and from different directions we had arrived in the same place. David tried tofu for the first time on our second date, and on our third he taught me how to make chicken noodle soup. (The secret is dill.) He stopped eating beef and pork. I started eating trout and turkey. He loved miso. I loved sushi.

He didn’t want to kill the lobsters. I thought that maybe I could.

“I should do it,” David said. “I’ve done it before.” Over his shoulder, I watched him ask Google whether lobsters feel pain.

We gazed at each other in glum silence. We felt guilty for falling apart when confronted with the reality of our food choices. We felt guilty for the distinctly first-world nature of our “problem” in a time when millions of people go hungry. We felt guilty for not being grateful for the gift. We felt guilty for feeling guilty.

In the living room, I could still hear them shuffling around in the box.

“Go meet your friends,” David finally said. “I’ll do it while you’re gone so you don’t have to watch.”

“No,” I replied, shaking my head. “I’m not leaving you. We’ll do it together.” I reached out and grabbed his hand. We opened the box.

Inside, under a layer of lime-green packing peanuts, were two lobsters. Frozen. Sealed in plastic. They had been dead all along.

We looked at each other, astonished. We’d really heard them moving around in there. Both of us had. As clearly as the ticking of a clock. As clearly as the telltale rhythm of a heart.

Nearly two hours had passed since the box appeared, and in that time seas rose and icebergs melted, lives ended and began, and the Earth kept spinning in the right direction. Meanwhile, two 20-somethings in an ant farm of a city poured an epic fugue of morality, change, sacrifice, childhood and compromise into a plastic-foam delivery box that was figuratively empty the whole time.

There’s an expression, isn’t there? Don’t sweat the sma—

The phone rang.

“So who took the plunge?” asked my friend.

“Neither of us,” I admitted. “They were dead all along.”

“My God,” she laughed. “I can’t wait to see what happens if you people have kids.”

Keenan is a freelance writer in New York.