actomyosin: a protein complex in muscle fibers; composed of myosin and actin; shortens when stimulated and causes muscle contractions
chemical: material produced by or used in a reaction involving changes in atoms or molecules
welwitschia: curious plant of arid regions of southwestern Africa having a yard-high and yard-wide trunk like a turnip with a deep taproot and two large persistent woody straplike leaves growing from the base; living relic of a flora long disappeared; some may be 700-5000 years old