Laurencia, a marine genus of Red Algae from Hawaii.

Algae (Latin "seaweeds", singular Alga) are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in land plants. For that reason they are currently excluded from being considered plants.

Some species of algae form symbiotic relationships with other organisms. In these symbioses, the algae supply photosynthates (organic substances) to the host organism providing protection to the algal cells. The host organism derives some or all of its energy requirements from the algae. Examples for this: lichens, coral reefs and sea sponges.

The Algal Collection of the U.S. National Herbarium (located in the National Museum of Natural History) consists of approximately 320,500 dried specimens, which, although not exhaustive (no exhaustive collection exists), gives an idea of the order of magnitude of the number of algal species (that number remains unknown).

Some uses: agar, alginates, energy source, fertilizers, nutrition, pollution control, pigments, stabilizing substances.

Antifreeze contains a rather subtle taste and smell that can easily be diluted and masked when combined with a hot liquid or a sweet tasting liquid. This exhibited itself as a problem after several cases, including the Julia Lynn Turner and Stacey Castor murder trials, showed antifreeze as a highly dangerous murder tool. Symptoms of antifreeze poisoning include severe diarrhea and vomiting and usually farther into the intoxication, signs of delirium, paranoia and intense hallucinations manifest. Antifreeze poisoning can be identified from the growth of calcium oxalate crystals in the kidneys.

Ethylene glycol poisoning is caused by the ingestion of ethylene glycol. Ethylene glycol is most commonly found as the primary ingredient of automobile antifreeze and hydraulic brake fluids. It is a toxic, colorless, odorless, almost nonvolatile liquid with a sweet taste. Following ingestion the symptoms of poisoning follow a three step progression starting with intoxication and vomiting, before causing metabolic acidosis, cardiovascular dysfunction, and finally acute kidney failure. The major cause of toxicity is not the ethylene glycol itself but its metabolites. The major metabolites causing toxicity are glycolic acid and oxalic acid.

Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License)

For more information (background, pictures, experiments and references): Algae, Antifreeze, Ethylene Glycol Poisoning