Two small melongs have come my way.  The larger one has a rainbow patina.  As well as the other uses of a melong, apparently they are placed on the stomach of a baby as a soother.  Aaah. 🙂

As well as what seems to be Yama, Lord of Death at the top,  the Chinese zodiac animals and the Eight Trigrams there are nine symbols in the centre.  here is an explanation kindly given pemachopel on the forum Vajracakra.com :

”Numbers 1-9. In Tibetan, these are called the me-wa gu. In English, this is a so-called magic square where any line added up across, down, or the hypotenuse through the middle equals 15. These nine numbers are correlated to the nine stars. It is a system of numerology/astrology. It was borrowed from the Tibetans from the Chinese, remembering that Tibetans use both kar-tsi (white or Indian astrology) and nak-tsi (black or Chinese astrology). (The white and black are abbreviations for the Tibetan for India, gya-kar, vast white, and China, gya-nak, vast black. One gloss of this is that the white and black are based on the color of clothes that predominate(d) in each respective country.) In Chinese, this system is called the nine star system and can be used as a complete system of divination. Each person is born under the influence of one of these nine stars and the relationship of these “stars/number” progresses in an orderly fashion according to the hour, day, month, and year, with good and bad “aspects.” Among Tibetans, each of these stars is associated with a deity. Therefore, they can be propitiated to avert bad influences. The whole diagram on the back of the melong is meant to protect one from all adverse astrological influences. Square versions are printed on paper and either folded up and worn as amulets or mounted in homes, places of business, etc. for the same reason. Propitiation of these deities is often specifically mentioned in various sang and ser-kyem offerings, as in “turn back/avert the bad influences of the me-wa gu,” etc.”

And from Wki:

” Lo Shu Square (simplified Chinese: 洛书; traditional Chinese: 洛書; pinyin: luò shū; also written 雒書; literally: Luo (River)Book/Scroll) or the Nine Halls Diagram (simplified Chinese: 九宫图; traditional Chinese: 九宮圖; pinyin: jiǔ gōng tú), is the unique normal magic square of order three. Lo Shu is part of the legacy of the most ancient Chinese mathematical and divinatory (Yi Jing 易經) traditions, and is an important emblem in Feng Shui (風水), the art of geomancy concerned with the placement of objects in relation to the flow of qi (氣) ‘natural energy’.

Chinese legends concerning the pre-historic Emperor Yu (夏禹) tell of the Lo Shu, often in connection with the Ho Tu (河圖) figure and 8 trigrams. In ancient China there was a huge deluge: the people offered sacrifices to the god of one of the flooding rivers, the Luo river (洛何), to try to calm his anger. A magical turtle emerged from the water with the curious and decidedly unnatural (for a turtle shell) Lo Shu pattern on its shell: circular dots giving unary (base 1) representations of the integers one through nine are arranged in a three-by-three grid.

The odd and even numbers alternate in the periphery of the Lo Shu pattern; the 4 even numbers are at the four corners, and the 5 odd numbers (outnumbering the even numbers by one) form a cross in the center of the square. The sums in each of the 3 rows, in each of the 3 columns, and in both diagonals, are all 15 (the number of days in each of the 24 cycles of the Chinese solar year). Since 5 is in the center cell, the sum of any two other cells that are directly through the 5 from each other is 10 (e.g., opposite corners add up to 10, the number of the Ho Tu (河圖)).

The Lo Shu is sometimes connected numerologically with the Ba Gua 八卦 “8 trigrams”, which can be arranged in the 8 outer cells, reminiscent of circular trigram diagrams. Because north is placed at the bottom of maps in China, the 3×3 magic square having number 1 at the bottom and 9 at the top is used in preference to the other rotations/reflections. As seen in the“Later Heaven” arrangement, 1 and 9 correspond with ☵ Kǎn 水 “Water” and ☲ Lí 火 “Fire” respectively. In the “Early Heaven” arrangement, they would correspond with ☷ Kūn 地 “Earth” and ☰ Qián 天 “Heaven” respectively. Like the Ho Tu (河圖), the Lo Shu square, in conjunction with the 8 trigrams, is sometimes used as a mandalic representation important inFeng Shui (風水) geomancy. ”