Dr Richard Willan (NT Museum) identified the photos of the juvenile posted here in July 2020. He notes:

"Unlike other gastropods, the mantle of cowries has the ability to produce colour and sculpture (in ridged and pustulose spp.) everywhere on its inner surface rather than just at the margin as the shell grows. At present the shell is moderately slender, thin and colourless. I went through every page of Burgess’ Cowries of the World book to match the characters of the mantle and siphon (which don’t change ontogenetically). The mantle in this individual has numerous, long, close-packed, slender, simple papillae with a dark middle zone. The siphon is fringed with very short papillae. All these characters are unique to C. tigris, so I think it has to be that species. The habitat – under rubble on reef at low tide – is certainly consistent with that of (all life stages of) C. tigris."