Assalaamu alaikum [peace be to you],
Here in this photo you can see decoration on the roof of the Minaret in the Niujie Mosque.
They're called imperial roof decoration or roof charms or roof-figures. Along the unions between the roof panels, near the corner, a row of small figures is placed. They form an outward marching procession. These beasts are considered as roof guardians and, according to the local [Un-Islamic] traditions, they are believed to "protect" the building.
Note that these figures have nothing to do with Islam. they are not part of Islamic culture or tradition. they are purely local traditional architectural elements in China.
the beasts in the photo are, from right to left, an imperial dragon, 4 heavenly horses and a lion. At the head of the procession should be a man riding a Phoenix (like other similar buildings). but instead here in the mosque we only see a lion.
More photos: nayzak.deviantart.com/gallery/…