Learn Farsi: من می‌خواهم لاک‌پشت کمیابی را که درباره‌ی آن صحبت کردیم، ببینم. - I want to see the rare turtle about which we talked.

In Farsi relative clauses (the part after که), you cannot easily move prepositions like "about" next to "which" as we do in formal English. Instead, Farsi structures it as "the turtle that we talked about it." The word آن (it/that) acts as a placeholder (a resumptive pronoun) inside the clause so the preposition درباره‌ی (about) has something to attach to.

Why is there an -i at the end of کمیابی (rare), and why does را come right after it?

The -i suffix here is the restrictive relative suffix. It links the specific noun phrase (لاک‌پشت کمیاب, rare turtle) to the describing clause starting with که (that/which). Because this entire phrase refers to a specific direct object that you want to see, the definite object marker را must follow it immediately, giving us لاک‌پشت کمیابی را.

Why is ببینم (I see) separated from می‌خواهم (I want) by so many words?

Farsi is a Subject-Object-Verb language, so verbs typically go at the end of their respective clauses. The core framework of this sentence is من می‌خواهم ... ببینم (I want ... that I see). Everything from لاک‌پشت to کردیم acts as one long object phrase sitting in the middle. Also, ببینم takes the subjunctive form because it is the second verb triggered by the verb of wanting (می‌خواهم).

How is the word کمیاب (rare) constructed?