The shell of Melo is ventricose, with a very wide aperture, and is large or very large. The largest shell is a specimen of M. amphora, reaching 520 mm in length, the smallest is M. tessellata reaching 272.6 mm. The number of teleoconch whorls ranges from 1 to VA whorls. The large protoconch is dome-shaped, with a diameter ranging from 10.2 to 13.8 mm, having a height of 2.3 to 7.6 mm, and consists of 2l/2 to 4 whorls. Usually, Melo species have spines on their shoulders that are formed on two sides with shell material, leaving one unshelled side. The number of spines varies from 5 to 18 and are up to 31 mm in length. They are erect, and either curved towards the protoconch or decumbent as in M. tessellata. Early growth of spines begins after a quarter to seven eighths of the first whorl, and their termination may vary, with some reaching the outer lip or stopping early. When the spine does grow to the outer lip, the top of the outer lip takes on an inverted 'V’ shape, but if the spine growth does not reach the outer lip, the top of outer lip is relatively flat.
In general, the shell of Melo melo is different from other species because it does not have shoulder spines. M melo and M. umbilicatus have both a depressed apex, the apex of M. melo can only be seen in juvenile or sub-adult shells. M. umbilicatus has a compressed shell, a depressed apex, and both the spire and protoconch are sunken. In mature shells, M. tessellata and M. umbilicatus have spines growing up to the outer lip, meaning that shell growth was always accompanied by the appearance of spines. In M. aethiopicus and M. nusantara n. sp., some specimens have spines reaching the outer lip, but in other specimens spine growth only reach to about the last quarter of the last whorl, so this appears to be a variable characteristic in these species. However, the termination of spines in all specimens of M. amphora and M. gajahmadai n. sp. occurs well before lip maturation, approximately ceasing from quarter to half of the last whorl.
The bathymetric range of the genus is wide. Melo specimens can be found in shallow water, but larger ones generally live at greater depths. By native fishermen compressor diving, Melo is found to a depth of 45 m. From deep-sea trawling in the Arafura Sea M. amphora and M. umbilicatus are found up to 80 m deep. Lobster fishermen using nets in Puger, south of East Java, have found Melo gajahmadai n. sp. up to a depth of 120 m.
The shells of species of the genus Melo with their very wide apertures have the largest shell volume of all the gastropod snails. Depending on the habitat and diet, there is variation in colouration on the inside of the shell aperture. A reddish-orange colour inside the aperture can be found in Melo aethiopicus, and occasionally in M. amphora, M. nusantara n. sp., and M. gajahmadai n. sp., whereas a white aperture is occasionally found in M. umbilicatus, and rarely in M. aethiopicus and M. amphora.

Distribution of Indonesian species:
The geographic distribution of M. melo ([Lightfoot, 1786]) in Indonesian waters is from Bangka Belitung Islands in the south through the Karimata Strait, between Sumatra and Kalimantan, and extends north to the Riau Archipelago off East Sumatra. In the Indian Ocean it can also be found in Sibolga, Northwest Sumatra. Outside Indonesia it is widespread, and can be found in Myanmar, Malaysia, Thailand, Vietnam, the South China Sea and the Philippines.
The distribution of M. tessellata in Indonesia is from the Riau Archipelago in the north, south to Bangka and Belitung Islands, the waters of East Lampung, the Sunda Strait, the Java Sea between Java and Kalimantan, and east to the Kangean Islands and northern Bali. Its easternmost location can be found north of Banggai Island in the Banggai Islands, Central Sulawesi. From the Bangka Belitung Islands to the Riau Archipelago, M. melo and M. tessellata occur sympatrically, but relatively few specimens of M. melo have been found compared to M tessellata. The presence of M. tessellata or M. melo in southern India and Sri Lanka requires confirmation.
Melo aethiopicus (Linnaeus, 1758) also has a widespread geographic distribution in Indonesia, from the Barrang Lompo Islands, and Banggai Islands in Sulawesi waters in the west to Taliabu Island, Obi Island, Bacan Island, Seram Island of North Maluku Province, and extending to other localities in Provincial Maluku: the Aru Islands, Kai Islands, and the Tanimbar Islands. It also extends to the west coast of West Papua.
In Indonesia, Melo amphora ([Lightfoot, 1786]) can be found in the Aru Islands, Maluku. M. umbilicatus which was previously only known from the Aru Islands, Maluku can also be found in several locations on the west coast of West Papua, in Indonesia and south of Seram Island, Maluku. Melo broderipii (Gray in Griffith & Pidgeon, 1834) is reported to be found in the north of Maluku and north of Papua (Poppe & Goto, 1992 and Morrison & Wells, 2005), but this species is not discussed in this paper due to the unavailability of study material. I agree with the opinion of Poppe & Goto (1992) and Morrison & Wells (2005) that it is M. aethiopicus rather than M. broderipii that is found in the Aru Islands, Maluku.
Melo nusantara n. sp. lives in the Indian Ocean at several locations in South Java and in Thousand Islands in the Java Sea to the waters between Sumatra and Kalimantan. Fossil specimens of Melo gajahmadai n. sp. are found at Pasir Ipis in the eastern region of West Java (Middle Pliocene) and at Sangiran in Central Java (Late Pliocene). Recent specimens are found in southern Central and East Java, the Indian Ocean; Bali and the Nusa Tenggara Islands such as Lombok, Sumbawa, Flores, Adonara, Lembata, and Timor. M. gajahmadai n. sp. is also found in the waters of South and Central Sulawesi such as the Barrang Lompo Islands, Pangkajene Islands and Banggai Islands. These two new species live in the waters of Cilacap, south of Central Java, the Indian Ocean, which are located differently.