Learn Finnish: Patsas lienee siirretty temppeliin. - The statue was likely moved to the temple.

It is formed using lienee (the potential form of the auxiliary verb olla) followed by the passive past participle siirretty. Together, they express that an action was probably done to an object in the past, translating to 'was likely moved'.

Why is the object Patsas in the nominative case here?

In Finnish passive sentences, a whole singular object takes the nominative case. If this were an active sentence (like 'Someone likely moved the statue'), the object would be in the accusative case looking like the genitive (Patsaan). Because the action is passive, it stays as Patsas.

Is siirretty formed from siirtää or siirtyä?

It is the passive past participle of the transitive verb siirtää (to move something). The statue is the object being moved. The intransitive verb siirtyä (to move oneself or to shift) would be used if the statue somehow moved on its own.

Why does the sentence use the illative case temppeliin (into the temple) instead of a static location case?

The verb siirtää implies physical movement to a new location. Finnish requires a directional case (answering 'where to?') for the destination of verbs expressing transfer or movement, so the illative case is used.