I've noticed this alien looking "thing" slowly drifting along the reef at the depth of about 10 m. It was about 4-5 m long, 30 cm in diameter. A flexible, hollow tube, so one could put an arm into it. Which I did.

Here are more pictures, with a dive buddy of mine for a scale, and some closeups:

It took me a while to find out, what it was. Egg mass of a diamondback squid, Thysanoteuthis rhombus.

15 minutes ago, Genady said:

It took me a while to find out, what it was. Egg mass of a diamondback squid, Thysanoteuthis rhombus.

As long as it doesn't join forces with octopuses and take over the world! 🤭

I wanted to see what other big squids are doing with their egg masses. Not much known, but here is an interesting recent finding:

This Mesmerising Underwater Blob Is Actually a Huge, Rare Mass of Squid Eggs (sciencealert.com)