The only question being: will we discover it soon, later or much later :)

Ah yes, that is a question I discuss with my students when we approach particle physics, It's a great way to show them that science is always a work in progress...

Actually, pentaquarks have been discovered too, by the LHCb experiment at CERN. See here.

Thank your for the link. I was not writing that the pentaquark has not been discovered yet, but that we still are not sure about its configuration: it is a real pentaquark or a combination of a baryon and a meson? In the link, the same question appears:
"the LHCb researchers conjecture that the pentaquark could be a tightly bound (spherical) system of all five quarks , or a “molecular” system consisting of a weakly bound baryon and a meson " (source:https://physics.aps.org/articles/v8/77)

For the list of all known particles (including baryons and mesons), I would refer to the Particle Data

Wow, I checked it out, this is pretty extensive! Thanks you!