It is documented here on the wiki due to being officially-released content by Mojang Studios, even if not present in a final version.
3D was a joke item from Java Edition 3D Shareware v1.34. Eating it shows a picture of the developer cast.
3D was dropped by a creeper summoned by the cheat code "NEEEERD".
Eating the 3D item when the hunger bar was not full shows a picture of the developer cast of Minecraft.
|Name||Namespaced ID||Form||Translation key|
|3D Shareware v1.34||Added the 3D item.|