TOPIC: Pearl of the Sirine questions

Is crushing a Pearl of the Sirine (to allow underwater spellcasting for a room) an instant action like dust or a standard action?

Also, would an Ioun Stone:Irridescent Spindle (which sustains the character without air) let a spellcaster use the Pearl or do you need a token that explicitly says allows breathing underwater?

If you're planning for next year, the intro video mentioned that you do not need special magic to breath underwater in the Silver Sea

A belated Thank You! to NightGod for your answer and to Druegar for adding "Standard Action" to the Pearl's listing.

A follow-on question: Does the Silver Sea also allow spellcasting underwater?
My search-fu is failing in finding the intro video, and multiple tokendb listings say that allowing underwater breathing does not by itself allow underwater spellcasting.