Immediately upon being put on, this ring cannot be removed. After the next long rest, the you discover, Wisdom (Perception) DC 1, a small arm (child sized for your race) has grown from your upper back. The arm loves you very much, like a needy baby, and constantly grabs things to hand to you, strokes your hair, grabs your ear, squeezes/picks your nose, pulls at your clothes, pats you excitedly, and ‘pouts’ when treated roughly.
A Charisma (Animal Handling) check DC 14 calms the arm for 30 seconds, results over 20 calm it for 10 minutes, over 28 for 30 minutes. Either you or another may make this check, but anyone other than the you has Disadvantage unless they have interacted with the arm on a daily basis for the last week. Anyone who has been a dedicated mother or father in the past has Advantage on this check.
If not in a calmed state, the arms has a 80% chance of interfering with whatever you are doing. Attacks and skill checks have disadvantage during this time and spell casting requires a DC 8 concentration check. At the start of your turn, if you are concentrating on a spell, you must make a DC 6 concentration check to keep concentration.
The ring can be removed by drinking a mercury/silver solution twice per day for four days. On the morning of the fifth day, the arm falls off and the ring can be removed.
(TrS) was way more desperate than expected to get this ring off of Rovert. We barely got to enjoy it, but I’m sure it will turn up again. Let me know in the comments how this new companion was received by your players.