polymorphs
More like two tetrahedrons stuck together.
A hexahedron or a triangular dipyramid. This is the shape formed by two triangular pyramids (tetrahedrons) stuck together along one triangular face.
Tetrahedrons. The patented drinks container 'Tetra Pak' is this shape. See 'Related Links' below.
yes
Tetrahedrons and quadrilaterals.
Tetrahedrons are triangular based pyramids that have 4 faces, 6 edges and 4 vertices which were built by the ancient Egyptians.
tetrahedrons
polymorphs
good question
tetra means four.
Two regular tetrahedrons connected face to face make a "regular triangular dipyramid." That is one of the 92 "Johnson solids." Those are the convex polyhedrons whose faces are regular polygons but do not belong to either of the two sets of highly symmetric polyhedrons (the Platonic and the Archimedean) or to the perhaps less interesting two infinite families of prisms and antiprisms. If the two tetrahedrons overlap, both centers at the same place but with the tetrahedrons facing in opposite directions, it makes a "stellated octahedron."
Silicate minerals.
More like two tetrahedrons stuck together.
go to your local game shop and ask for a d8
Regular tetrahedra don't, in the sense that they don't fit together in an arrangement that fills space with no gaps.