The answer to your question is Vegetative Propagation.
Vegetative Propagation is defined as a form of asexual reproduction of a plant. It occurs when only one "parent plant" is involved in producing an offspring that will be genetically identical to the parent.
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I think the answer to your question is Magnetic.
<span>One can infer from this situation the following things: first, the fertilizers used in the farm eventually get to the adjacent river. Second, these fertilizers may be providing some benefitial conditions to the algae, allowing it to grow exponentially and strongly.</span>
They are buried in the core of the structure.