Minecraft wiki entry for Beacon, associated text: The texture file for the beacon in Java Edition 12w36a was laid out almost identically to that of the end crystal.
The then-texture file for end crystals for comparison; note the identical layout.
First image released by Jeb.
One of the many uses for the beacon.
The old texture from Java Edition 12w36a of the beacon.
The old texture from Java Edition 12w38a displaying the powered and the non-powered beacon.
The texture of the beacon used from Java Edition 12w40a until the Texture Update.