MADRID (Reuters) - At least 10 melon-sized ice balls that have slammed into Spain in the last week are probably debris from comets, not human excrement as first suspected, a Spanish scientist said Monday.

Enrique Martinez, head of a team at the Higher Council of Scientific Investigation studying the phenomenon, said it was first thought that the ice balls were human excrement ejected from high-flying aircraft.

"But they lack the typical coloring and texture we find in those cases," he said.

A man in southern Spain escaped injury last week when an eight-inch ice ball weighing nine pounds smashed into his car.