Today I've received the Japanese version of the Donkey Kong 64 guide, published by Kodansha - the maps in this guide have been rendered in 3D, so it was my hope that perhaps they too would have recreated the Ice Key Chamber in Crystal Caves.
Luckily, my purchase was instantly validated when I flipped to the Crystal Caves section to reveal that, yes, the 3D map did in fact feature the Ice Key Chamber, and what's more, there's even a bit of text on the side that questions it.
Crystal Caves 3D
Obviously, the gameplay screenshot had been replaced at this point, but they missed the text in the process, which reads (roughly translated):
"A mysterious item!?"
"I can't see inside, but there must be something in the room. When will it open here?"
"^ With a powerful Chunky, can't you break it?"