I finally decided to stop being lazy and make a starter. I had some older DME in a ziplock in my beer stuff drawer - so I boiled a cup of that in about 6 cups of water for 5 minutes... but now that it's cooling down, there are bits of floating stuff on top. I guess this is just stubborn DME that refused to dissolve.
Is this OK to use? I haven't pitched any yeast onto it yet, so it won't cost me much to chuck it out and go get some new stuff if need be. This is in prep for a high gravity expensive beer (clone of Chimay Blue - expected OG 1.089) and I don't want to start off on the wrong foot.
Here's a pic - that pot was clean before adding water and DME to it: