If you have been playing Destiny 2, and have purchased the Curse of Osiris DLC, you will be aware that the game is filled with new resources. One of the resources that has been dropping for players in Fossilized Hermaion Blossom. It has been confusing players, as it does not seem to have a function, yet.
It is safe to assume that this resource is needed to complete Lost Prophecies, and to make the related weapons in the Forge. The specifics of why this resource drops are not yet known, but two of the TL;DR crew got it from doing a Nightfall, so it seems to be connected to that activity at least.
At this point, and knowing what we do about the Lost Prophecies, anything that drops into your inventory that you cannot use right now should certainly be kept, as it may be very important quite soon.
For now, there are other resources in the game that you definitely need to make the Lost Prophecy weapons in the Forge. If you need to know how to farm them, we have guides for Concentrated Radiolarian Culture and Advanced Paradox Amplifiers.
You will need both of these resources to build the currently available Lost Prophecy weapons in the forge, and will almost certainly need them to build future ones, as well as your Fossilized Hermaion Blossom. Should you need help with other aspects of Destiny 2, be sure to check out our helpful Guide Hub.