University of Bristol physicist Ruth Oulton tells Live Science that the algal opals are made from lipids in a tightly packed lattice structure. However, in most organisms the opals are hard. Rainbow wrack is “the first time that an opal’s been found that’s not made of hard material inside a living thing,” she adds.
The lattice changes shape depending on the amount of sunlight. “What we know is seaweed itself can change [its] opal … when it gets lighter, the opal structure disappears,” Oulton said. “When [a] beetle dies, the opal is still there, but if the seaweed were to die, all of it would disappear.”
Oulton’s team thinks the finding could be used to make biodegradable displays and in biodegradable packaging labels. Their work was published in a recent issue of Science.