Joyal’s species constitute a good framework for the study of algebraic structures associated to com-binatorial objects. In joint work with Marcelo Aguiar, we studied the category of species focusing particularly on the Hopf monoids therein. The notion of a Hopf monoid in species parallels that of a Hopf algebra and reflects the manner in which combinatorial structures compose and decompose. We constructed examples from combinatorial and geometric data inspired by ideas of Rota and Tits’ theory of Coxeter complexes.