Sara Bareilles makes horrifying discovery behind unopened door inside her home

Moments later, she recoiled in horror over the stomach-churning sight.

“It’s a skull … it’s a skull … the bone of a maggot-filled skull,” she said in disbelief.

Behind the door? A revolting mix of black soot, dirt and what appeared to be decomposing animal carcasses.

“I don’t know what this thing is. It’s a giant dragon. What the f–k?!” she shrieked.

Bareilles quickly slammed the door shut, but the damage was done.

In a follow-up clip, the shaken singer returned armed with gloves and a paper bag, revealing she had never managed to open the mysterious door before — until debris spilling out forced her hand.

Peeking inside again at the gruesome discovery, she described a “carcass and remains of some kind of giant rodent.” Her best guess is a raccoon … or something worse.

With a garden shovel in hand, the Broadway star removed the rotting mess only to uncover even more horror.

“This body is big. It’s like a turkey,” she said, before screaming.

“Oh my God, it’s like birthing itself backwards. There’s multiples. It’s multiple things!”

Bareilles scooped the remains into a bag, later admitting simply: “That was traumatic.”

She even joked that her recent binge of the survival show “Alone” helped prepare her for the grisly task.

“I won’t give any spoilers, but you got to be tough,” she said. “If one of those contestants had encountered this, they would have boiled the bones.”

Instead, Bareilles opted for a more peaceful sendoff, saying she planned to give the creatures a “little blessing” before returning them to nature — despite them being “very dead.”

Bareilles’ “Girls5eva” co-star Busy Philipps couldn’t handle the footage.

“It is so vile,” Philipps said while laughing and screaming in an Instagram Story. “This is the worst HGTV show I’ve ever seen in my life … she’s braver than I am.”