For what did the ancient Romans use a Corvus?

In this context, the corvus (crow or raven in Latin) was a boarding ramp that allowed them to get on enemy ships from their own vessels, while both were at sea. In the First Punic War, it was found to be particularly useful in battles with the Carthaginians, though not when there were rough sea conditions.

The reference below describes the corvus and its operation in detail.

https://en.wikipedia.org/wiki/Corvus_(boarding_device)