Learn Icelandic: Sjávarlíffræðingurinn elskar það að lífveran hefur mikla vitsmuni. - The marine biologist loves the fact that the organism has great intellect.

The phrase það að translates nicely to 'the fact that.' It acts as a bridge, turning the entire following clause into a noun phrase so it can be the direct object of the verb elskar. Because elska requires an object in the accusative case, the pronoun það is technically in the accusative here.

Could það change its case depending on the main verb in sentences like this?

Yes! The pronoun það changes case to match what the main verb demands. Here, elska takes the accusative, so það is accusative (which looks identical to the nominative). If the verb required the dative case, you would see því að, and if it required the genitive, you would see þess að.

Why is the phrase for 'great intellect' plural here (mikla vitsmuni)?

The Icelandic word for intellect or intelligence, vitsmunir, is a masculine noun that is almost exclusively used in the plural. The verb hafa (has) requires the accusative case, so we use the accusative masculine plural for both the adjective (mikla) and the noun (vitsmuni).

How is the long word sjávarlíffræðingurinn constructed?