If those are all the faces then it is a 26-hedron. There is a Greek prefix for 26 but unless you want to be pretentious and unhelpful, I would not bother with the prefix.
They are called polygons
A box is a 3D shape with 6 rectangles (a box could also include squares). The rectangles are: Top/Bottom/Front/Back/Side/Side
Regular tessellations can be made using triangles, squares, and hexagons.
a geometric shape made up of 20 triangles. :)
It doesn't exist. The least number of sides for a 3-D shape only made of triangles is 4.
It is a 26-hedron and there are more than one configurations for the shape.
A cube
The shape is a triangular prism. This is a 3-dimensional polygon with two ends that are triangles and three rectangular sides connecting them.* * * * *FYI, a 3-dimensional polygon is known as a polyhedron.
A cube is made out of squares ONLY. A Pyramid is out of triangles and sometimes with squares.
a star
A pyramid could be constructed from 4 or more triangles.
Polygon
A regular tetrahedron
No. Platonic solids, as their name suggests, are 3-dimensional objects. A triangle is 2-dimensional.
It is a three dimensional figure of some sort.
A dodecagon is a 12 sided shape made from 10 triangles
None. A polyhedron is 3 dimensional and you cannot make a 2 dimensional shape out of 3D shapes.