The dry fruits of the ironwood are called nutlets.

The fruits are not visible in the photo. Rather, we can see involucres, a whorl of modified brown, hairy leaves that hide the fruits.

In botanical terms, this is not a fruit: it's an accessory fruit. It is formed when several flowers of an inflorescence form fruits and fuse together. The strawberry is a good example of this type of accessory fruit.

This dry fruit cannot open spontaneously. It is similar in construction to acorns and hazelnuts.