In memory of the man who put red and green squiggles under words (devblogs.microsoft.com) Tony Krueger is remembered in Wikipedia as the person who ported the game Chip’s Challenge to Windows for the Windows Entertainment Pack.¹ But that’s probably not the code he wrote that touched the most people.
The main effect of extrusion is that the magma can cool much more quickly in the open air or under seawater, and there is little time for the growth of crystals.