Allusions tend to become visible only when, for some reason, they demand a response yet, like unreciprocated handshakes, fail to be grasped.
Some eye patterns became visible only when the caterpillars were molested and expanded part of their body, and some large specimens wriggled and rattled like snakes.
The notes also have iridescent stripes and a special dark security line that become visible only when held up to a bright light.
Comets, which travel around the Sun in orbits that extend beyond Jupiter, are cold, dark objects that become visible only when they approach the Sun.
The swastika, sprayed by an unknown vandal with a chemical that became visible only when floodlights came on, has become the most potent symbol of a rise in ultra-nationalist sentiment that appears to be bleeding into the mainstream population in the EU's newest member state.
Instead, they ramble across the English countryside and crisscross small-town streets to create their art: enormous virtual drawings of a fish, a boat and other figures that become visible only when the path of each journey is reproduced later, at a smaller scale, on the Internet.
All the city layers we discussed above share this dynamic, even if they are far more complex than a hammer: they are invisible while we use them to achieve something, they become visible only when a problem emerges.
In cancer tissues, hidden variants exist and they become visible only when pairs are created.
These results indicate that genetic benefits may interact with the environment, and thus benefits of extra-pair mating are likely to become visible only when conditions are relatively unfavourable.
The lag phase for AβpE3 42 becomes visible only at the lower concentrations.
