Seen today on the beach at Easthaven. Not a clue what this is but there were similar (but brown) jelly like things next to it as well.
DSC_2505 by davidmamartin, on Flickr
..d
I'd say they were enormous alien lifeforms, possibly 300 metres across, devouring large parts of that mountain range they landed on.
Oh, wait a minute.....are those millimetres?
Units of measurement not specified. You, of all people, David.