The Eltreum (ヱルトリウム) is a high-tech spacecraft which was used to reach the center of the galaxy for the final battle against the Space Monsters on May 22, 2048. It is the largest manned spacecraft ever built by mankind. Like the Exelion, it was piloted by Tatsumi Tashiro. Unlike its predecessors, which used more conventional propulsion methods, the Eltreum is propelled by the power of pure mathematics and controlled by ESP-enabled porpoises.
The Eltreum is a large 70km long triangular craft. Since the only episode it appears in is in greyscale, its true color it unknown, but it appears to be white.