1 Dollar - Elizabeth II Yellow Sponge

Tuvalu's novelty coin program, administered through the Perth Mint under licensing arrangements, produced a run of species-themed issues in the early 2010s aimed squarely at the collector market. The yellow sponge — a marine invertebrate common to Indo-Pacific reef systems surrounding the Tuvaluan atolls — gave the series a degree of geographic relevance that many such programs lack. Mintage on these Perth-struck collector pieces was tightly capped, and secondary market attrition is low given that virtually none entered circulation.