Unknown shrub in my garden

Unknown shrub in my garden

Observation - Unknown shrub in my garden. Description: Plant has thorns and larger leaves with small ones on stem in between. Fruit attach directly to stem in pairs - most unusual to me. Found growing under a leylandii. Thought they were apples at first but fruits are hard and full of seeds. No idea what it

Plant has thorns and larger leaves with small ones on stem in between. Fruit attach directly to stem in pairs - most unusual to me. Found growing under a leylandii. Thought they were apples at first but fruits are hard and full of seeds. No idea what it is!