The Manimals were intended to be the next phase of the "Lunartix Empire Star Brigade" figures. Six figures were planned for late 1994 - but the G.I.Joe line was cancelled before these figures hit the stores.
Each a different kind of alien, all the Manimals had a transforming ability. In addition, the Manimals were larger in size than regular 3 3/4" figures.
Unlike the similarly cancelled Ninja Commandos, a few dozen loose and perhaps one dozen carded Manimals samples are available in the collector's market. However, these Manimals figures are NOT easy to find and are NOT cheap.
Because they were never released in stores and because of their uniquely rare nature, the Manimals are an unrealistic goal for the completist G.I.Joe collector. But they are an interesting example of what might have been, had the G.I.Joe line not been cancelled in 1994.