If you fly into the USA with a Casascius coin worth more than 10k do you have to disclose it legally?

Basically the title.

Custom’s and Border protection mention this:

Money" means monetary instruments and includes U.S. or foreign coins currently in circulation, currency, travelers' checks in any form, money orders, and negotiable instruments or investment securities in bearer form.”

I hate the IRS and FinCin, but the coin seems like a bearer asset a bit to me, since the private key is physically on the coin.

(Last I heard BTC is treated as property, not a currency).