Look a lot like tiny apples. (Oak Apple?)
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yes this looks like oak marble galls. they develope as a result of distoration of leaf buds on oak trees by gall wasps, which lay aggs within the leaf buds. the gall is first just a mass on green plant tissue filled with a wasp larva which hardens and becomes a brown colour. the gall provides the larva with a micro habitat and protection from predetors.
Lat/Lng: 52.7, 1.6
OS grid ref: TG4920