In geometry, the elongated bipyramids are an infinite set of polyhedra, constructed by elongating an n-gonal bipyramid (by inserting an n-gonal prism between its congruent halves). There are three elongated bipyramids that are Johnson solids: Elongated triangular bipyramid (J_14), Elongated square bipyramid (J_15), and Elongated pentagonal bipyramid (J_16). Higher forms can be constructed with isosceles triangles.