Today I found a live Lightning Whelk on the beach, partially buried in the sand.  I thought it was part of an empty shell, and picked it up, but it was not empty.  I have never found a live whelk before.

I put the snail down and he started to work his way down into the sand again. Here is a video:

When I came by later, he was mostly covered up again.

The Lightning Whelk's egg mass looks like this: