What type of pearls are these?

This strand is very peculiar. It alternates 2 real pearls then 2 faux pearls all the way through. It is a very long strand and the string l broke one pearl to see what was inside. Any thoughts??

Here's more images

Handmade by someone who liked that aesthetic or who just wanted to experiment a bit. Maybe they didn't have enough FWP to make as long a necklace as they wished so they alternated with imitation pearls.

That's the nice thing about making your own jewelry-- you can do whatever you like with it. Try different threads, different arrangements. Include other beads. Whatever.

The pearl you broke apart is a solid nacre FWP (tissue nucleated, no bead.) The FWP are low quality generally.