What is the purpose of blue crystals in Darksiders 2?

About an hour ago I've started playing Darksiders II and I've wandered into 2 of these blue hovering crystals that make a sort of continuous church bell sound. I've tried to get near to them but I didn't manage to find a path to them.

Here's a screenshot of one of them:

Are these interactable and if so what do they do or are they just a part of the scenery?

Ben's answer is technically right, but not very detailed, and the post he links to is quite misleading. I'm going to put the rest of this in spoilers, so only mouse over if you want to know what they are.

The crystals are a food of sorts for a construct named Blackroot. You do not have to wait til you get the Tremor Gauntlet to collect them, as they can be broken with Redemption, after you talk to Blackroot, who can be found in the Western bend of The Fjord.