A Pineberry, of course!
The pineberry is white and covered in red pips and has the same genetic make-up as the common strawberry but with a flavour and ''extraordinary'' smell closer to that of the pineapple, Waitrose said.
The supermarket will sell pineberries in 45 stores across the UK for the next five weeks while they are in season.
The pineberry originated in South America as a wild variety of strawberry but was threatened with extinction until seven years ago when Dutch farmers began growing it commercially, according to the retailer.
They are grown in glasshouses, turning from green to white and are ripe when the seeds turn dark red.
Nicki Baggott, Waitrose fruit buyer, said: ''Pineberries offer our customers the chance to add a new fruit into their diet and the berry's bright appearance can add an unusual decoration to sweet dishes.
''As the summer unfolds we won't be surprised to hear that our customers are inviting their friends over for pineberry pavlovas, punch or serving them up with yogurt for a lighter alternative.''
A 125g punnet of pineberries will cost £2.99 until April 13 and then sell for £3.99.