Which fruit has its seeds on the outside?

The seeds of a strawberry are actually outside the flesh of the fruit and clearly visible.

The sweet red flesh of the strawberry is not the fruit. It is a part of the flower called the receptacle that is located below the ovary. The receptacle swells to attract animals so that they will eat and scatter the true fruit. These are the small yellow seed-like parts, which are a dry fruit called an achene.

The strawberry is a fruit, but it's not classified in a way you might expect. Despite its name, the strawberry is not a "true berry" because it lacks the thin skin and pericarp (three layers formed from the wall of an ovary) that botanically define a berry.