Someone - maybe Barbara Damrosch? - recommended cocoa hull mulch, so when I saw some at Roxbury Mills I grabbed a bag. I've used it just on containers, and I like the look, although chocolate is a strange smell in the garden. Yesterday I noticed white mold on the mulch! Yuck - but it's apparently common in wet, humid weather (which we've had for weeks) and totally harmless.
Weirder than that is what happens to Soil Moist granules when you spill them on the ground. As soon as it rains, they swell up and look like transparent jello.