The material is stainless steel 304, it is better for outdoor used.
This dolphin sculpture with mirror finish, so it looks very smoonth and shiny if put it under the sunshine.
For matching mirror finish, the main process is what we can see in this video: polishing.
After many workers time and energy, they polished the surface and welded points time by time to make it looks it an mirror.
But I think it is worthy as the dolphin looks very cute and beautiful.