Weird things to find on a dive

Took some fresh Open water students on a tour of Whytecliff Marine Park today when I noticed a peculiar piece of debris on the sandy bottom it looked like this:

What is it?

This object fits in the palm of my hand and is quite durable, as it doesn’t fall apart when handled.

I just learned what it was a week ago so I was pretty excited to show it to the new divers.

This strange spiral is a Moon snail egg cluster, like nudibranch they lay eggs in a ribbon but this ribbon contains sand and is not to a rock but left loose on the sandy bottom. Watch for them on your next dive!

I am wondering if they are seasonal since it is only recently that I have started noticing them.