Mushrooms... i turn the wavemakers off, use a razor blade, cut a shroom off leaving a little base to grow back, then take the whole head (or cut it into 2 or more pieces)and let it sit in a container with rubble and verrrry little flow, and be patient, enough flow that the water is circulated but just barely. They will attach to rubble with 2 weeks, IME
Palys...
Here