David is correctamundo. Kanegon (Kane=money = gon from Dragon) was a creature who originally appeared in the whimiscal segment of ULTRA Q, entitled "Kanegon's Coccoon" (Kanegon-no Mayu). This was Episode 15. An especially greedy boy named Kaneo, trades for a funny coccoon which sounds like it contains coins. Obessed with money and incredibly stingy, overnight Kaneo's coccoon swells to fill the boy's room. The next morning, Kaneo rejoices at the wealth that must be contained inside, but instead is sucked into the coccoon and transforms into Kanegon -- a creature that must ingest money or die. I would go on, but I don't want to spoil it anymore than that.
In the original ULTRAMAN series, they showed many of the past Ultra Monsters in the opening credits as stylized silhouettes. Kanegon did not appear in ULTRAMAN. The Kanegon that appeared in the movie ULTRAMAN ZEARTH 2 was a robot version of Kanegon. The money-muching monster has also appeared in several other series and specials.