A tetrahedron, an octahedron or an icosahedron,
triangular prism
An octahedron
A 3D shape with all triangular faces can be a tetrahedron pyramid.
An octahedron.
tetrahedron
The shape you are describing is a regular octahedron. An octahedron has eight equilateral triangular faces, with all faces being congruent. It is one of the five Platonic solids, characterized by its symmetrical structure and equal edge lengths.
A triangle based pyramid.
A triangular pyramid has.
You're an octagon.
A regular octahedron.
Octohedron, or rhomboid.
Icosahedron are a shape with 20 faces, 30 edges and 12 vertices. All the faces are triangles.