Pursuit by Lester del Rey, Science Fiction, Fantasy 12+

📙 He was a soft egg in a vast globe of elastic gelatine. Two creatures swam menacingly through the resisting globe toward him. The gelatine fought against them, but they came on. One was near, and made a mystic pass. He screamed at it, and the gelatine grew stronger, throwing them back and away. Suddenly, the creatures drew back. A door opened, and they were gone. But he couldn't let them go. If they escaped....