I have been scouring the internet for an answer to this very question. I have canned for a number of years but only got into canning meats with a pressure canner for 2 years now. After Thanksgiving I decided to can turkey broth. I also followed Ball Book exactly. I had never experienced all that pinging before! I caught a sale on chicken quarters, canned the meat with no problem and then canned the broth with all that pinging again! Might it have something to do with canning liquids only? The seals are all good but are the contents safe? The only answer I found was one lady who said she leaves her broth sit in the canner for at least an hour after the pressure has fallen before she removes the lid and that solved her ping problem. I have not used any of my canned broth yet since I was searching for an answer as to whether or not it was safe. I will try leaving it sit for an hour the next time.

I remember the ball idea used as a 'wet/dry' system for aquariums, particularly saltwater systems.( I used to have a pet store and have not messed with an aquarium since.) The idea was as water cascaded through them nitrogen wastes would be converted to nitrates. It was to enhance the surface area of the filter substrate. For worms I think it would work as place to collect material and maybe some cocoons, but would be nightmare to collect castings from. I'd like to see somebody try them out, but it won't be me.

Bahama Strongbark?

CC, I found a free collage site: https://www.photocollage.com You can change backgrounds, resize, etc. Just add in what pictures you want. It’s crude (due to user/me being tech challenged), others here have way better photoshopping apps and abilities! :)