UFO - Season 1 - Eps 23: The Sound of Silence
A UFO hides in a lake on a country estate of a well-known equestrian, and the equestrian himself vanishes. When SHADO tracks down the UFO and manages to destroy it in an exchange of pot-shots, the UFO breaks up and leaves a thing floating in the water. Treated as if it is a bomb, it is brought back to SHADO and examined, with unexpected results.
About UFO

Title: UFO
First Air Date: 1970-09-16
Last Air Date: 1973-03-15
Status: Ended
Rating: 7.6/10 (from 45 votes)
Language: EN
Seasons: 2
Total Episodes: 26
Network: Associated Television
Genres: Sci-Fi & Fantasy, Drama, Action & Adventure
Production Companies: Century 21 Television, ITC Entertainment
Synopsis
A secret, high-technology international agency called SHADO defends Earth from alien invaders.
Cast

Ed Bishop
Cmdr. Ed Straker