The 1787 "Horned Bust" Connecticut Copper is one of the most popular varieties of the entire series because of the eponymous "horn" that projects from the front of the bust in the lower left obverse field. The horn is actually a chip in the die that builds in size over time. Early states of the obverse die are perfect and show no trace of a horn. A small chip develops in the die and appears on the coin as a raised chunk of metal floating in the field. As the striking sequence progresses, the horn becomes longer and larger, eventually attaching to the mail and arching further into the field. There are so many variations of the size and length of the horn that some collectors create a specialized collection showing this interesting die progression.
High grade, circulated examples can be found with relative ease. Mint State examples are extremely rare. PCGS shows only two MS62BN examples in their Population Report (as of December 8, 2018).