Black smoke ooze from the dead worms.
Zera had to learn that they couldn't inhale the black smoke from the worms they killed.
It was poisonous.
Hence, they couldn't come out until the rain passed and the wriggling worms disappeared and stopped emitting black smoke.
In short, they were trapped at the moment.
"You may seem invincible, but don't let it get to your head," Xavier whispered.
Zera glanced his way, a smirk on her lips.
"Just admit it," Zera replied, following his whispery tone. "You are partially intimidated."
Xavier shook his head, a grin spreading on his lips.
"I am," he mockingly agreed. "I am intimidated by you a lot."
Rolling her eyes, Zera aimed for another corner where much of the black worms gathered. They were leaving the ground with their poisonous slime.