Usually possessed by specialized collectors, a Casascius coin is a tangible Bitcoin unit that is available in a variety of forms, sizes, and sorts.
Casascius coins, created by Mike Caldwell in 2011, are a few of the earliest known examples of so-called "physical bitcoins." The term "physical bitcoins" refers to BTC that is kept inside a tangible object, like a coin or bar. Mike Caldwell produced Casascius coins until 2013, when the Financial Crimes Enforcement Network intervened and forced him to cease production. They thought the action might be regarded as money transmission and hence call for a license.
Mike created and added value to 27,938 Casascius coins and bars during the course of his three-year effort, with a total estimated value of 91,262.8 BTC. Casascius coins are viewed as a desirable investment prospect because of their rarity.