Temple of Koopa
From the Super Mario Wiki
The Temple of Koopa is a series of underground caverns located in Jungle Land that was said to be built by King Koopa's Great Great Grandkoop, which he chose to build as a place to hide the Lost Mushroom. Although Kolonel von Koop never learned about this on his own, Indiana Joe did, as he knew the location of every hidden treasure in Jungle Land. The entrance to the Temple of Koopa is shaped like a crowned Koopa's head, presumably that of its founder. The interiors consist of many boulder, mushroom and torch-filled tunnels, as well as a chamber where the Lost Mushroom was housed. At least one Fryguy and a Cobrat are known to inhabit the Temple of Koopa.
The Temple of Koopa made its first and only appearance in The Super Mario Bros. Super Show! episode "Raiders of the Lost Mushroom". Mario, Luigi, Princess Toadstool and Toad had traveled to Jungle Land in search of the Lost Mushroom, and eventually encountered Indiana Joe, who, upon hearing their request to lead them to Lost Mushroom, brought them to the Temple of Koopa. Having spied on them, Kolonel von Koop and the Koopa Pack followed them to the Temple of Koopa, and opted to wait outside while the heroes recovered the treasure.
Indiana Joe displayed his Koopaphobia to Mario and his friends, and showed that he couldn't possibly enter the Temple of Koopa, so they ventured in without him. Shortly after entering the Temple of Koopa, the ceiling caved in, blocking the exit. A Fryguy soon attacked Mario's group with fireballs, and chased them through the Temple of Koopa's many tunnels. After leaping over a large Cobrat, Mario's group sealed themselves inside the chamber where the Lost Mushroom was, and Mario claimed it. Wanting a way out, Mario inadvertantly wished for a trap door, and the Lost Mushroom granted his request, opening up a passage underneath the group, which transported them to the Temple of Koopa's entrance. After this venture, the Temple of Koopa was never seen or referenced again.