SOMA Crystal
SOMA News 6 Jan 2005

rhōma - a slanting SOMA

Picture of the Rhoma Game In 1989, Marvin Solit developed a puzzle, which is a rhombic version of Soma.
He called it rhōma.
Each block of the puzzle is a rhombic hexahedron, one of nature's building blocks. It contains the same angles as the carbon atoms (used in organic life) beehives and many crystals. When rhōma is solved, it is in itself a rhombic hexahedron.

The very special property of rhōma, is that it has only one solution.

Until 2004 it was manufactured by Design Science Toys, but the company is now out of business. However Marvin has a few (about 4) left, so if you want one, it might be purchased for $25 each (US) plus shipping.

So: rhōma is a modern version of the classic Soma puzzle.
The shipping weight is 0.75 pounds(US)
The dimensions are 5 in x 5 in x 2.50 in (US) about 12,5 * 12,5 * 6,5 cm (Europe)
The cubic pieces of the Soma puzzle is slanted into rhombic angles, a dramatic sculpture and a challenging puzzle with only one solution. This one is a real mind-bender!

The rhōma puzzle contains 7 different maple pieces in a wooden base, and a puzzle solution.

Together with the rhōma puzzle you find a small description, reading:

This puzzle is a transformation of Piet Hein's Soma Cube, whose seven pieces combine in more than 200 ways to make a larger cube. Rhoma uses the rhombic transformations of these seven pieces, but there is only one way that they will go together in their cradle to make a rhombic hexahedron.

1. Place the three-armed piece called 'Wingo' in the center of the cradle, arms up.
2. Rest 'Righty' and 'Lefty,' which are mirror images of each another on either side of 'Wingo,' leaving a hole in the center.
3. Stand Z shaped 'Ziggy', in the hole resting on 'Righty'.
4. Stand 'Tom', the T shape, next to 'Ziggy.'
5. Wrap 'Victor', the V shape around 'Ziggy'.
6. One space remaining for 'Ella' the L shape.
rhōma in pieces

Here's the solution in SOMA notation:
/. . . ./. . . ./. V B B
/. . . ./.V.B.P./. Z Z B
/L P P ./.V.Z.Z./. T T T
/L A P ./.L.T.A./. . . .
/L A A ./. . . ./. . . .
rhōma label

Submitted (24.dec.2004) by Marvin Solit <>
Foundation for New Directions, 93 Belmont Street, Cambridge, MA 02138 USA.

It is 11 May 2021 and Jim Allen (near Richmond, Virginia, USA) wrote to me.
"I received a blue SOMA cube for a Christmas present, about 1977.
My Dad loved puzzles, both physical models and logic puzzles, and the it inevitably rubs off on his children.
We still have many of his puzzles, though he died 20+ years ago.
One of Dad's puzzles is a wooden SOMA cube that is tilted and slanted so each face is an identical rhombus,
I think the figure is called isohedral rhombohedron. I solved the puzzle and made a video of the solution."
So below, you can see Jim's interesting video, comparing the assembly of a SOMA and a rhōma.

To see this movie, press the ▶ in the left side of this picture.

Edited by Thorleif Bundgaard <>
Addition by Jim - T J Allen <>

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