A moonquake is an earthquake, but on the moon. It means that there could be something underneath the moon's surface causing the event to happen. Moonquakes are measured by rovers.
Someone or something that bites your ankles.
To a postman, an ankle biter is often known as a dog.
To an adult, an ankle biter may be a toddler.
To hikers, an ankle biter is sometimes a tick.
And so on.