Middle English fom, fome (c. 1300), from Old English fam "foam, saliva froth; sea," from West Germanic *faimo- (source also of Old High German veim, German Feim), from PIE root *(s)poi-mo- "foam, froth" (source also of Sanskrit phenah; Latin pumex "pumice," spuma "foam;" Old Church Slavonic pena "foam;" Lithuanian spainė "a streak of foam"). The plastic variety used in packaging, etc., so called from 1937.
<a href="https://www.etymonline.com/word/Styrofoam">Etymology of Styrofoam by etymonline</a>
Harper, D. (n.d.). Etymology of Styrofoam. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/Styrofoam