Is it an island or just a rock?

Is it an island or just a rock? This is a game that all island collectors must play from time to time and a question to which there is no definitive answer.  I rejected the following tidal locations off the Isles of Scilly because they either had no vegetation on them or were clearly joined on to another larger island above high tide level or because they are unnamed.

 

Tresco from Green Island

I haven't included this as an island, as it has no vegetation on it apart from some lichen.

Green Island from Skirt Island

"Ermintrude" Rock, Skirt Island, Tresco

I rejected Skirt Island, as it is clearly currently joined to Tresco well above high tide level.

Periglis, St Agnes from an unnamed island

This island has enough grass to graze a sheep and is only joined to St Agnes by a man-made rocky causeway, which I presume was built to create a harbour.  However the island has no name.

Kallimay Point, a tidal island off St Agnes

Kallimay Point, St Agnes

I rejected Kallimay Point, as it has no vegetation on it.