Why do I need to open an Acorns Checking account to get the Mighty Oak card? Alexander G. Updated November 13, 2023 16:03 The Mighty Oak card is a debit card, which allows you to easily access the funds in your Acorns Checking account. Was this article helpful? Yes No 0 out of 0 found this helpful Have more questions? Submit a request Comments 0 comments Article is closed for comments.