The series revolves around a family of robot-like beings who are called upon by an Earth boy whenever a giant monster appears initiated by Goa, a space alien. The one summoned by three whistles is the eponymous Magma, who fight the monsters.
The dub of this series was known as The Space Giants. It cut minimal scenes but still changed names. For example, Magma became Goldar, while Earth became Methusa (after the 900-year old man in The Bible) The opening was not kept, but the music within the show, including uses of the famous theme tune, was.
An animated OAV was produced in 1993 which retold the story. It was pretty much universally panned.
Ambassador Magma provides examples of the following tropes:
- Monster of the Week: Subverted somewhat in that the monsters are used multiple episodes, like a serial.
- Transforming Mecha: Possibly the Trope Maker. Magma/Goldar is capable of transforming into a rocket.
- Robot Hair: Magma/Goldar is a "living giant" forged from gold with long gold hair. His normal-sized, human-looking wife and son are also behaired, but it's less unusual on them.
- There Are No Adults: Goa's apparent motivation for his invasion of Earth (or so he says) is to make a literal world where this is in effect and children can be happy. Okay, but... what happens when the kids grow up?