Foreign Body (conceptual sci-fi, 81,000 words).
"Your thoughts depend on your body," said the green alien with eyestalks.

Physician Dave Booker is shocked to discover an alien living in his summer cabin. Phane, the alien, is an anthropologist from another star system. His shuttlecraft has crashed, and he must regain it before the mothership gives him up for dead. But Dave is dumbfounded by the alien's appearance, a large, green tennis ball with two eyes on tentacles above his head. What would it be like to have a body like that? Does our body determine how we think about the world? Dave's ambitious boss captures Phane but he escapes. In a wild chase, Phane flees determined pursuers including the military, but it's not easy for a talking green tennis ball to hide. Dave realizes that Phane has much to teach humanity, but can he find his green friend first and help him?