You're missing some information to calculate the snail's rate of movement! To figure out the rate, we need to know how many hours the snail traveled for.

Here's how we can calculate the rate:

* Rate = Distance / Time

Let's say the snail traveled for 2 hours. Here's how we'd solve it:

* Rate = 0.5 meters / 2 hours

* Rate = 0.25 meters per hour

Please provide the number of hours the snail traveled, and I can calculate the rate of movement!