what was this kids tv show?

[CiderMonkey]

my brother asked me the name of this uk kids tv show and i kind of remember it but only vaguely.
was on tv in the v late 80's or early 90's - was about man who was an alien, he used to wear a shell suit and had some kind of metal band/bracelet on his arm with a stone in it that had some kind of power.
He lived with a family and the boy of the family was his friend.
My brother seems to think the aliens name was short, about 4 letters. and for some reson i think he may have lived/hid in the shed.

Any ideas? we've googled to death!

[ermintrude35]

mike and angelo?

[curiosity]

Watt on Earth? http://www.imdb.com/title/tt0199285/

[curiosity]

http://www.sausagenet.com/program.asp?mode=vie w&progid=961&progname=Watt+on+Earth
this seems to say a bit more