Abalone is a shellfish that you can eat and that has a shiny substance called mother-of-pearl inside its shell. a kind of shellfish which is used as food and whose shell contains mother-of-pearl. Any of several marine snail species (genus Haliotis, family Haliotidae), found in warm seas worldwide. The outer surface of the single shell has a row of small holes, most of which fill in as the animal grows; some remain open as outlets for waste products. Abalones range from 4 to 10 in. (10-25 cm) across and up to 3 in. (8 cm) deep. The largest is the 12 in. (30 cm) abalone (H. rufescens). The shell's lustrous, iridescent interior is used in ornaments, and the large muscular foot is eaten as a delicacy. Commercial abalone fisheries exist in California, Mexico, Japan, and South Africa