They resemble ornaments, but the two dark pinecone-shaped objects in the photograph have a working purpose. They are the kind of metal weights used with traditional mechanical cuckoo clocks.
Hanging from chains, the weights gradually descend under gravity. Their movement supplies power to the clock's mechanism. Winding a chain-driven clock raises the weights again, giving them room to travel downward through another running cycle.
The shape is familiar enough that replacement clock weights are still sold in this pinecone style. Their mass varies to suit different movements, so appearance alone does not tell you which clock a particular weight belongs to. That combination explains the original puzzle: an object can look decorative while being too heavy for a tree ornament because its weight is precisely what makes it useful.
Sources: Cuckoo Clock Shop: How Do Cuckoo Clocks Work? American Cuckoo: Custom Weight-Driven Clocks Original linked story