Antique or vintage (?) black coral (?) necklace

Hello CW fellows! It is quite a while since I posted or visited CW. Hope you are all well.
I have this old necklace that I bought thinking it was glass but when it arrived I had a mystery to solv. It feels very light and is very shiny or polished. Have been searching online all day and now I wonder if this is actually a carved black coral necklace? What do you think? It has little inperfections that makes me think this is a natural material. Looks very much like black coral jewelry I have found on line but I haven't found another one in this design. Need advice to be sure.
The necklace is 31 cm long and each "shell" is about 2,5 cm long. It has a hidden screw bead clasp. I am certain the material is not shell. It feels like when holding amber, a bit plastic but at the same time not. Shell normaly feels colder when you hold it. That is my experience.

Greatful for input on the material and age so thanks in advance!