“It’s the MacGuffin of the series,” showrunner Issa Lopez tells EW.

Warning: This article contains spoilers forTrue Detective: Night Country, episode 2, “Part 2.”

“That’s the filmmaker’s problem when you have the writer’s cap on.

True Detective Season 4

Navarro (Kali Reis), Danvers (Jodie Foster), and Prior (Finn Bennett) stare at the corpsicle in ‘True Detective: Night Country’.Max

So obviously when I sent it to the studio, they were like, ‘What are you thinking?’

And I said, ‘You’ll see.’

But I had no idea,” she recalls with a laugh.

True Detective Season 4

Prior (Finn Bennett) and Danvers (Jodie Foster) investigate the corpsicle in ‘True Detective: Night Country’.Max

But she knew she had no choice but to figure it out.

It is so center.

It’s the MacGuffin of the series," she says.

True Detective Season 4

Prior (Finn Bennett) gets up close and personal with the corpsicle in ‘True Detective: Night Country’.Max

Max

So, she started with a pretty gnarly mental image: a rat king.

You don’t know how many shrimp are there in that block.

So let’s think like that,'" she says.

“Each of their expressions had to be specific,” Lopez says.

“And for that I thought of Mexican mummified bodies.

We have that in Mexico.

And as a kid, I saw them and they were engraved in my mind.

So those expressions of agony come from mummified bodies.”

“And my sound engineer turned to me, white-faced, and said, ‘You called itwhat?’

And I was like, ‘The corpsicle.’

And he said, ‘That’s not in the series.’

And I said, ‘Oh my God, you are right!'”

“And,” she concludes, “all of that came together, and voila, corpsicle.”

True Detective: Night Countryairs Sundays at 9 p.m. ET/PT on HBO.