There are many such shapes: a sphere, ellipsoid, toroid all have no flat faces.
Any one of the intersected by one plane will have one flat face, if intersected by two planes, there will be two and so on.
Amongst polyhedra, only a tetrahedron (or triangular prism) fas fewer than 5 flat faces.
A tetrahedron has four faces and six edges.
A shape that has fewer than 8 faces and fewer than 10 edges is a triangular prism. A triangular prism has 5 faces (2 triangular faces and 3 rectangular faces) and 9 edges. It meets the criteria of having fewer than 8 faces and fewer than 10 edges.
A shape that has more faces than an octahedron (which has 8 faces) but fewer faces than an icosahedron (which has 20 faces) is a dodecahedron. A dodecahedron has 12 faces, satisfying the condition of having more than 8 and fewer than 20 faces.
A shape in fewer than 3 dimensions.A shape with one or more curved faces or edges.
Hexahedron
A dodecahedron
octahedron
A polygon that has more faces than a hexahedron (which has 6 faces) but fewer than a dodecagon (which has 12 sides) is an octagon, which has 8 sides. Additionally, a nonagon, with 9 sides, also fits this criterion. Both shapes meet the requirement of having more than 6 faces and fewer than 12.
Prism.
yea
4
Sphere is the answer.