I found the following websites using the wording "Many Treasures."

There is also a Buddha called the Many Treasures Buddha.



http://nichirenscoffeehouse.net/Ryuei/God-is-Kanzeon.html

When she does finally accept, after the Buddha asks her to, she splits the offering between Shakyamuni Buddha and the stupa of Many Treasures Tathagata. ...
nichirenscoffeehouse.net/Ryuei/God-is-Kanzeon.html - 19k - Cached - Similar pages


http://lotus.nichirenshu.org/lotus/lectures/lotus_25.htm

The above website refers to:
"the stupa of Many Treasures Buddha"
"stupa of the Many-Treasures Buddha"




Buddha of Many Treasures

http://www.mit.edu/~stclair/Lotus21.html



http://sokaspirit.org/resource/lb/2000-09-01.shtml

The above website refers to:
The Daishonin used the stupa or “treasure tower”
and
Many Treasures is a Buddha who appeared, seated within the treasure tower at the Ceremony in the Air, in order to lend credence to Shakyamuni?s teachings in the Lotus Sutra

Here in Southeast Asia there are many beautiful stupas that hold the treasures and relics of Buddha.


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Note added at 1 day7 hrs (2007-04-11 01:40:25 GMT)
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"Stupa of the Many Treasures Buddha" combines the word "stupa" that holds the many treasures with the words "Many Treasures Buddha" that is at the stupa (site.)

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Note added at 1 day8 hrs (2007-04-11 03:15:36 GMT)
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Yo-san, just a note:
This is a personal preference (and a generally prevalent method) but I like to use capital letters when writing "Buddha" or the many forms of Buddha: Future Buddha, Many Treasures Buddha, etc. for respect. (Although I also see the word written with small letters, too)

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Note added at 1 day9 hrs (2007-04-11 03:28:06 GMT)
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(I do that with names of the revered in all religions--it's a natural reflex) :-)

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Note added at 1 day9 hrs (2007-04-11 03:45:37 GMT)
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If "stone" is necessary here are some alternatives:
stupa of the Many Treasures Buddha (stone)
stupa of the Many Treasures (stone) Buddha

I plugged 多宝塔 into Google, and here's what the top link said.

宝塔とは
ほうとう　宝塔
日本に於ける仏塔の一形式で、平面円形の塔身に方形屋根を架けた一重塔。
これに裳階（もこし）を付けて二重にしたのが多宝塔であるが、はじめは両方とも多宝塔と称した。

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Note added at 27 days (2007-05-07 14:51:48 GMT) Post-grading
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I forgot to mention that the above Infoseek page contains abundant schematics, with part names.

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Note added at 27 days (2007-05-07 14:53:46 GMT) Post-grading
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Wikipedia (http://ja.wikipedia.org/wiki/多宝塔) says
多宝塔（たほうとう）は、寺院建築のうち仏塔における形式のひとつである。現代の寺院建築用語・文化財用語としては、二重塔であって、初重平面が方形、二重平面が円形のものを指す。

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Note added at 27 days (2007-05-07 15:07:20 GMT) Post-grading
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Then again, this could be a reference to 多宝如来.
The Wikipedia article (http://ja.wikipedia.org/wiki/多宝如来) starts off with
多宝如来（たほうにょらい）は、仏教の信仰対象である如来の一つ。サンスクリットではプラブータ・ラトナと言い、「多宝」は意訳である。

FWIW, my favorite Buddhist 意訳 is 不動 for Acala, the Immovable One.

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Note added at 29 days (2007-05-09 12:38:17 GMT) Post-grading
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More data presented itself to me, quite coincidentally, today.
多宝如来=Prabhutaratna
http://www.flickr.com/photos/maynard/491127216/ (series of four photos)
http://eng.buddhapia.com/_Service/_ContentView/ETC_CONTENT_2... Buddhapia rendering of the Shakyamuni-Prabhutaratna encounter