At 16mm, that will be the 1/16th dollar.
Though usually filed under "British West Indies", because that's one place where they circulated, the "anchor money" was Britain's attempt at creating an Empire-wide dollar-based currency system, for use throughout the Empire, in the hopes of displacing the Spanish dollar from its premier position as the most popular trade coinage at least throughout territories under British control. Most of these coins were actually sent to Mauritius, with only the remainders of the 1822 issue sent to various colonies in the Caribbean. The Anchor Money experiment was abandoned after just two years of issue, 1820 and 1822.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis