ELI5 Pasta - did Marco Polo really 'invent' it?

Why does pasta foam when the lid is on the pot, but the bubbles quickly disappear if I lift the lid? If all pasta is made from the same ingredients, why do we have so many pasta shapes? Did Marco Polo introduce pasta to Europe or was it all a marketing tale?   ... We explain like i'm five!   Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: 77to90, sandor, sweetmercy, ipodpron, apoorva63, thegreatlakesarefake, ktlrj, walnutsnail, varialectio and pigeoncanfly To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: [email protected]