The tritetrahedron, also called the "boat polyhedron," is the name given in this work to the concave (non-regular) octahedron
formed by joining three regular tetrahedra
around a common edge and dropping inner faces. It is therefore precisely a 3-tetrahedral
ring.

Rather surprisingly, the net shown above gives the triterahedron using the edge labeling of the left figure while the labeling shown in the right
figure gives the usual regular octahedron.

de Grey, A. "A Small 6-Chromatic Unit-distance Graph in ."
Geocombinatorics30, 5-13, 2020.de Grey, A. and Haugstrup,
A. "Two Small 6-Chromatic Unit-Distance Graphs in ." Geocombinatorics31, 110-115, 2022.