I cannot even imagine a 15 lb bulb! Holy Toledo!
The ones that I have around my apartment and in my backyard are huge plants, in my opinion, for being bulbs. I've seen Amaryllis bulbs and consider those to be large. You said that yours, Moonhowl, are considered Giant Spider Lilies? I can't imagine larger than these that I have out here now...so Wow! Would LOVE to see one of those. I'm going to go now and see if you've posted any photos of them!
Closing off the thread now as solved. Thanks again to everyone...you all have been so very helpful!