Biscoito de Polvilho is a kind of breadstick made with tapioca powder and is extremely crumbly and crunchy. One popular brand is Biscoito Globo which is made in Rio de Janeiro and is a trademark of Rio de Janeiro’s beaches. The packages are sold by vendors walking on the beach and pairs perfectly with mate tea which is also sold on the beach.

https://en.wikipedia.org/wiki/Biscoito_de_polvilho