The 20 pentarhombs each consist of five rhombi and belong to the family of polyrhombs. These game pieces are composed of rhombi arranged in a rhombic grid. In contrast to polycubits, the interior angles of the rhombi do not necessarily have to be 60° or 120°.

Pentarhombs and the well-known pentominoes are structurally similar. For the I, T, X, and U pentomino, there is a direct equivalent among the pentarhombs. The remaining eight pentominoes each correspond to two different pentarhombs.

In total, there are: 1 dirhombus, 3 trirhombs, 7 tetrarhombs, 20 pentarhombs, 62 hexarhombs, and 204 heptarhombs.

Shapes made from all 20 pentarhombs cover an area of 100 rhombi. This allows the construction of a diamond-shaped figure with edge length 10. A smaller version of the same pattern, with edge length 5, can be formed from only 5 pentarhombs.

The underlying rhombic grid permits shapes with at most two axes of reflection and 2-fold rotational symmetry. Beyond that, there are also more asymmetric shapes featuring only a single axis of reflection or pure 2-fold rotational symmetry without any reflection axes.

The puzzle was developed with support from the PolySolver program.

Each pentarhomb shape can be enlarged by combining multiple pieces: to double size using 4 pentarhombs, to triple size using 9, and to quadruple size using 16 pentarhombs. One exception is the X-pentarhombus — no solution exists for constructing its double-size version from 4 pieces.

The 3D-print templates consist of the 20 pentarhombs along with one large and one small box.