Fronted by highly assertive female vocals, this Frankfurt quintet was formed in 1973 by guitarist Pit Hensel and bassist Claus Kniemeyer; musically, they followed in the tradition of Frumpy, Ruphus, Earth & Fire.
Between 1976 and 1981, they released four albums of which the first two, "The Boat of Thoughts" (76) and "An Ocean of Rocks" (78), are by far considered their best. The subsequent "Rubber Angel" (79) and in particular "Hart Am Rand" (81) which features a male singer, are unfortunately not on par with the first two.
Perhaps leaning more towards rock than prog, their music crosses over various musical lines, mixing classic prog elements such as multiple rhythm changes, and straight-ahread rock with a little bit of blues thrown in. Searing guitars dominate the mix but you'll also hear plenty of synthesizer and some fine keyboard solos.
As for Jennifer Hensel's gritty alto voice, it suits the band's hard-edged approach rather well - for comparison's sake, imagine a cross between Janis Joplin (without the grit) and Jennie Hahn from Babe Ruth.
If you're into early Eloy or like some of the bands above, you may want to check out Octopus' first two albums, starting with "The Boat of Thoughts".