Ok, so here is literally ALL of the info I could find:
Strombus luhuanus Linnaeus, 1758]
Description: Shell solid and heavy, conical in overall shape; spire variable in height. Early whorls usually smooth, sometimes with axial folds, rest of shell smooth and glossy. Aperture elongate; columella smooth, lightly calloused; outer lip with deep posterior and stromboid notches. Columella black, outer lip orange internally; deep ******** of aperture pink. Exterior white or pink with about seven spiral brown bands on body whorl, with axial zigzag lines, more prominent in spiral bands. Operculum corneous, long, thin, serrated. Periostracum brown, thick.
Size: Up to 73 mm in length.
Distribution: Indo-West Pacific. In Australia, Torres Strait, Queensland, southwards to Shellharbour, NSW; also offshore reefs in north-western WA and a few isolated records on mainland north-western WA.
Habitat: Among seagrass in intertidal and shallow subtidal. Abundant in tropics, uncommon in NSW.
Remarks: In the tropics this species occurs in high densities in isolated colonies. Depending on the availability of suitable habitat the colony may migrate, usually a distance of the order of hundreds of metres per year. Population structure and movement characteristics were studied in populations on the Great Barrier Reef and in southern Papua New Guinea by Catterall and Poiner (1983). Around Sydney, the species is known from only a few colonies in areas of suitable habitat. Juvenile shells (Fig. 3) do not have the expanded lip and stromboid notch so characteristic of adults.
Strombus luhuanus Linnaeus, 1758. The strombid, te nouo, is common throughout much of the low intertidal and shallow subtidal areas of Tarawa Lagoon. It also occurs on sandbars with mixed sand and coral rubble that rise to within 0±2 m below the surface. Like other strombids, te nouo is an herbivore and feeds on algae attached to hard substrata (Abbott 1960). It often occurs in large colonies. Maturity is reached within 2 yr after settlement, at which time shell length stabilizes at 40±60 mm, and the shell lip thickens.
Looks like they eat algea, which mine certainly does!