The State and all of its public officers, municipal corporations, political subdivisions, and public bodies, all banks, bankers, trust companies, savings banks and institutions, including savings and loan associations, all investment companies, insurance companies, insurance associations, and other persons carrying on an insurance business in the State, and all personal representatives, guardians, trustees, and other fiduciaries in the State may legally invest moneys or funds belonging to them or within their control and available for investment under other provisions of law, in any bonds or other obligations issued by the board of land and natural resources, and the bonds and other obligations of the board or agency shall be authorized security for all public deposits and shall be fully negotiable in the State. It is the purpose of this section to authorize any of the foregoing to use any funds owned or controlled by them, including (but not limited to) sinking, insurance, investment, retirement, compensation, pension, and trust funds and funds held on deposit, for the purchase of any bonds or other obligations; provided that nothing contained in this section shall operate to relieve any person, firm, or corporation from liability for failure to exercise reasonable care in selecting investments or, in the case of a guardian or trustee, from liability for failure to exercise the judgment and care to observe the duties required of a guardian or trustee by article 8 of chapter 412 and § 554-6.