This planet/life form is very, very interesting; but something tells me they're going to end up a casualty of the war.
My first thoughts were
Avatar, both for the 'tree-hugging' all-life-is-joined-together Gaia philosophy, and for the giant aerial vs. the giant tree. But, my later thoughts were of
TOS episodes
Errand of Mercy and
Day of the Dove when Federation and Klingons were forced to make peace, and were forced to fight respectively. And non-corporeal aliens. This planet seemed like a diversion, but instead it is going to have some central role in the plot.
I'm prettly sure we had episodes in Star Trek with crystals like that. Not a good idea to be around them.
Maybe you are thinking of
Is There in Truth No Beauty? when there is an ambassador inside a box that no one is supposed to look at him or go mad? Or Dilithium crystals, which featured many times, but while powerful never changed personalities? Or the Andromeda aliens?
Knowing the First Officer had been compromised, why would the Lieutenant have confided in him, or touched that crystal? Suru might've lost the fear for the first time in his life, but would that really have caused him to act against the best interest of the Federation?
I don't like Saru or maybe I just don't like Kelpiens and their cowardice.
I think he is just badly written/developed. I can't see how he would ever have evolved. I can understand Larry Niven's
Pierson's Puppeteers, who are evolved herd animals, and who have brains in their torsos, and who roll up into a ball when challenged, but Kelpiens are just humans who are slightly more cowardly.
And why does that female Klingon's every facial feature give away exactly what she's truly thinking? Has she had absolutely no training in deception?? (Or is she just a bad actor?)
For L'Rell, see my previous answer about Saru above.
I'm not sure what this episode was all about. We didn't really get any further forward plot-wise. Everyone is going to assemble at Pahvo. The Federation have lost a lot of ships and all the Klingon ships now have cloaking devices. Stamets is going crazy, but we already knew that. The Burnham and Tyler relationship continues to develop, but can never be fulfilled because she is going to prison. L'Rell's request to defect goes nowhere, but was it actually real? And she cryptically mentions that Voq was lost to her rather than dead, keeping alive that conspiracy theory that Tyler is Voq.