The four oxygen-sequence WR stars, Sand 1 in the Small Magellanic Cloud (SMC), Sand 2 in the Large Magellanic Cloud (LMC), and WR 102 and WR 142 in the Galaxy represent the latest stage of the evolution of massive stars (Sanduleak 1971, Barlow and Hummer 1982, Moffat et al. 1985). We have shown WR 102 to be a stripped CO core of a supermassive star (Dopita et al. 1990), probably seen only several thousand years before a SN explosion. The four stars are characterized by extremely energetic stellar winds –Vw from 4500 to 7400 km/s (Barlow and Hummer 1982, Dopita et al. 1990, Torres et al. 1986). Examination of the environments of WO stars leads to the conclusion that the four objects appear to be associated with optical and/or IR shell-like structures, although the short WO-superwind does not prevail in the shell's formation.