Strange find

We don't usually find mussel shells and seaweed in the garden! Strong winds or dropped by a bird??
Like most places in S of UK today, a very stormy day. Don't think I ' ve ever seen seas like today- waves so powerful. 
We have friends staying with us for a couple of days - we met at antenatal classes 33 years ago and been friends ever since. So lovely to catch- up face to face.