Conversation so far:
What was Billy Joel doing musically in 1965?
Joel joined the Echoes, a group that specialized in British Invasion covers.
The Echoes began recording in 1965.
What was the name of the first recording by the Echoes?
Joel played on a demo version of "Leader of the Pack".
Did they do mostly covers?
Joel states that in 1964 he played on a recording of the Shangri-Las' "Remember (Walking in the Sand).
What other songs did The Echoes do?
CANNOTANSWER.

Question: What did he do after being in The Echoes?
Self-contained rewrite: What did Billy Joel do after being in The Echoes?