Happy MerMOO to you! Blank Birthday Card £1.50 Quantity: at £1.50 each Add To Basket 24 in stock. Tweet Happy MerMOO to you! And what better way to say Happy Birthday than with this MOOtastic birthday card! Depicting MerMOO Olive and some fishy chums. All cards are BLANK inside and come with an envelope as standard. MerMOO Olive is award winning! If only ordering cards please use FREEDEL in the checkout.