Leopard Earthball?

I haven't come across the Leopard Earthball (Scleroderma areolatum)  often so my identification of this group is a bit tentative. It looks right and the habitat is correct (a damp earthbank under oak) and the size is also consistent (much smaller than the common earthballl at about 2-4 cm) so I'm sticking with it until someone wise tells me something different.