- Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. In contrast, intrusive rock refers to rocks formed by magma which cools below the surface.
- Defender (1981 video game) (Wikipedia)
Defender is a horizontally scrolling shooter developed by Williams Electronics in 1980 and released as an arcade video game in 1981. The game is set on either an unnamed planet or city (depending on platform) where the player must defeat waves of invading aliens while protecting astronauts. Development was led by Eugene Jarvis, a pinball programmer at Williams; Defender was Jarvis’s first video game project and drew inspiration from Space Invaders and Asteroids. Defender was demonstrated in late 1980 and was released in March 1981. It was distributed in Japan by Taito.