A pentagonal prism, a hexagonal pyramid, a cube with one vertex (corner) cut off, a tetrahedron with three vertices cut off - these are some of the possibilities.
Pentagonal Prism
A Pyramid is a 7 lettered 3D shape with triangular faces.
A heptagon.
Heptagon
heptahedron
A pentagonal prism.
pyrimid
heptahedron
heptahedron
a square
A hexagonal prism.
Hexagonal prism