While the Nydus Canal was an extremely useful means for obtaining reinforcements from two distant Zerg settlements, its role stopped there. With new evolutions, the Nydus Canal gave way to the Nydus Worm – a giant invertebrate which can move from place to place, giving the Zerg increased effectiveness in providing reinforcements. It first has to swallow all the Zerg units that it will vehiculate around - and the Nydus Worm can store inumerable amounts at a time. Once it is filled, it will burrow and tunnel its way to its destination, emerge brutaly with a deafening, blood-curdling roar, and slide back to ground level and vomit its passengers out. Although one Nydus Worm can spill forth an army of Zerg, the process can be quite lengthy, so bringing more than one can be highly advantageous.