Assertion: kelp's holdfast | /r/AtLocation | muddy substrates
Facets:
Source sentences:
text: The holdfasts of organisms that live in muddy substrates often have complex tangles of root-like growths, while those of organisms that live in sandy substrates are bulb-like and very flexible, such as the holdfast of sea pens, allowing the organism(s) to pull the entire body into the substrate when the holdfast is contracted.