The star-shape crystals look like ascidian/sponge spicules but they should have been dissolved by acid treatment (unless their skeleton has been replaced molecule by molecule as in radiolarian extraction).

Good luck for further id!

Best

I agree with Bruno. Those look like ascidian spicules. Although identification from transmitted light is more challenging than SEM pics, you can see their crystalline structure (they are most probably aragonitic). More precise assignment would be problematic from these pictures, but the one from the picture 1402.2 could be some Didemnum species  "(...) namely

D. membranaceum Sluiter, 1909 is characterized by similar spicules (Kott 2004, fig. 19g). There is also D. candidum described by Van Name as D. candidum fusiferum (1945, fig. 37), in which some of the spicules are of similar shape." (like the spicules illustrated on the Fig. 2 W, X of my latest paper).

If you need a more precise assignment you should consider taking SEM photographs of these spicules. You definitely have some shallow water (?) marine deposits mixed up with volcanic sediments there...

Dear Bruno and Magdalena,

thank you for your thoughtfulness and efforts. I know that these micro-objects can turn into good article. I would be happy if you collaborated with me on this article.

I will try to see the 3D structure of the crystals and find out their formula SEM and, I'll also get a Stratigraphic column and Geological Setting from field geologist and other geologists. I will probably take more detail on the dinoflagellate and foraminiferal paleontological study for stratigraphy.

I hope you will fully collaborate with me on this article.

Best wishes,

Jafar