Marble color IBIS may be well-known to Pelikan pen lovers, but information on it is limited. There were three (four) colors; gray, red, green, (deep green) for the pen (Pelikan Schreibgeräte, Pelikan-collectibles). The production period is unclear (according to Pelikan-collectibles, it was 1936-1942). As "NOS" IBIS in Fig.2 has CN nib. So, we can tell that marble color IBIS was still produced in wartime. According to Pelikan-collectibles, marble color IBIS was destined for the export market. 

The most striking feature is its body. The construction of the barrel is completely different from other Pelikan pens. But, it was rather commonly made, as other manufacturers did (e.g. Kaweco, Soennecken and OSMIA): marble celluloid is welded with transparent celluloid. That’s why there is no step in the barrel between marble body and ink view (Christof Zollinger).