The incident of the plastic honeycombs washing up on Thiruvanmyur beach

14th October morning.  Around 745 am

It was raining on and off, so I decided to head out to the beach, as I knew low tide was around 845 this morning, and I love walking during low tide on the beach front.

The rain had kept many walkers away, and for a moment I experienced that wonderful feeling of being alone and surrounded only by waves, the gentle hiss of the receding foam, wet sands, cool breeze and cloudy skies.  A tern flew by low over the water, north to south, and fishing boats were in the horizon.

However, the weather had not deterred the photo shooting couples and their camera teams, and I dodged my way around them as I began walking.

A large Sunset Siliqua and many bits of colourful shell were embedded in the sands.  A crow pecked hopefully at a closed mussel but to no avail.  Ghost crabs scuttled in and out of their holes.  There was the usual human-made debris - from poop, to lost slippers, empty glass bottles, cut onions, flowers and thermocol bits.  

And then I saw one little plastic honeycomb like this, and then another, and then some more.  As I walked along I realised there were many!

Soon, I had picked up a handful, and placed it along with the other stuff that the Urbaser cleaning crew had gathered up.  I asked her what she thought it was.  She wondered if it was from a juice bottle.

I asked a shore fishing lady the same question - she looked at it and said she didn't know and sounded like she had better things to do than solve my "id" problem.

There were just too many.  I found an empty plastic bag, and started counting and putting them in to it.  I had reached a count of 85, when a curious beach dog came up and started sniffing the bag.  I assumed he would lose interest, as he smelled the plastic, but no, he seemed to gain interest and gave the bag a firm tug.  I let it go- discretion being the better part of valour and all that - and waited at a respectful distance.  The dog sniffed the spilled contents, looked at me with disgust but would not budge!

Photographic evidence of the said dog, with plastic bag and plastic honeycombs strewn on the sand.

I waited for a couple of minutes thinking if the dog moved on, I could maybe put the contents back in, but no, he stayed put.  So I went back to the cleaning crew lady and told her my tale of woe, and how this plastic was all over the beach.  She cheerfully promised me she would clean it up.

I continued to walk and continued to count, and crossed a hundred.  I noticed, they were coming in with the waves - they were being washed up from the sea - not going into the sea here if you know what I mean.

What were they?

ChatGPT informed me - "That specific geometry — short cylinders with internal cross-fins — is distinctive to engineered biofilter media, not to packaging, toys, or consumer plastics.

• Used in moving bed biofilm reactors (MBBR) and fixed-bed filters.
• Designed with that honeycomb structure for bacteria colonization.
• Made of HDPE or PP, so they float — explaining how they end up on the beach.
• Found in large quantities when filters overflow or are cleaned out improperly."

I searched some more and it seems confirm that these kind of plastic bits are used for "good bacteria" to colonise, as they offer a really wide surface area.  MBBR (Moving Bed Biofilm Reactor) or similar biofilter carrier media — the kind used in wastewater treatment, fish hatcheries, or aquaculture systems.

So why are they getting washed onto the beach then?  Seems to be some accidental release into the drains or sewers?  Was it heavy rains or a careless maintenance flush that caused this?  I think I shall send a report to the TNPCB, what say?