On Malta, what fastened itself to Paul's hand as he put sticks on the fire?

Answer: A viper

A viper, driven out by the heat, fastened on Paul's hand, but he shook it off into the fire and suffered no ill effects.

“Paul gathered a bundle of sticks, and as he laid them on the fire, a viper, driven out by the heat, fastened itself to his hand.”— Acts 28:3 (BSB)