Just to  clarify:

It's not "any" funds.

It's limited to the Roth IRA annual contribution (it's in lieu of the contribution process, so an offset) for each year, and the beneficiary has to be eligible for contributing (has earned income). There is a max lifetime amount per beneficiary of $35k, so that's over 5 years minimum. It's still subject to the Roth IRA 5-year rule, so no contribution made in the most recent 5 years would be eligible yet. The 529 account for the designated beneficiary must have existed for at least 15 years.