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Things on shells and stones
        ... and plastic ...and seaweed

 

 

 

Holes

 

It is not unusual to find shells with tiny holes in them. If you happened to be a mollusc detective, this would be your biggest clue as to who murdered your mollusc and their motive. These tiny holes are made by the tiny drilling 'tongues' of carnivorous sea snails.

 

The culprits are likely to be dog whelks, whelks and necklace shells (more about them here) and they drill through the shells to get to the soft bodies inside which they turn to goo and suck up. It can take them days to drill these holes and the bi-valves inside have little chance of escape.

Many holes

 

A shell with a whole heap of holes (generally not uniform in size), has generally fallen prey to a boring sponge. before you all fall asleep, that's 'boring' as in boring holes, not boring you into a stupor. The sponge bores holes in its host to give it shelter. Unfortunately, this eventually kills the sea snail as the shell becomes brittle and falls apart. 

Limpets

 

If you find a limpet with a hole in - have a look at this page, before you go any further as it may be a (keyhole) hole that the limpet has grown there deliberately.

 

Mollusc eggs

 

These paper things on a razor shell are the eggs of sting winkles. Have a look here for more information.

 

They are also commonly found on sea weeds.

Barnacles

 

Barnacles have larvae which swim around looking for somewhere solid to settle. This can be rock, or stones (like the slate here), shells, pieces of plastic, the bottom of boats, the shells of crabs and turtles or the skins of whales. They are really, it would seem, not very fussy at all. 

Once the barnacle has settled, it cannot move and so, if the shell or stone gets beached, so does the barnacle and, out of water, it cannot survive for long.

 

Below are barnacles on a plastic plant pot (left) and a mussel shell (right). The ones on the mussel shell are the most likely to be alive as their trap doors are still intact.

 

There is more on barnacles here.

These white marks are the remains of barnacles. Here, they are on the black plastic of a lobster pot tunnel, but they can be found on pretty much any piece of plastic, stone or shell. Like barnacles themselves, they range in size from a few millimetres across to a couple of centimetres.

 

 

Bryozoan

 

It looks like a pretty white flower drawn onto a stone but it is actually a colony of a type of bryozoan - tiny animals which feed by waving tentacles in the water.

 

Keel worms

These tubes on a piece of slate (and a painted topshell below) are actually the tubular homes of worms. Have a look at the page dedicated to worms to see what's inside...

Stones with holes in

 

Please see our page on stones.

Things on seaweed

 

Sea mat

 

This white layer can cover a whole piece of seaweed. It is a colony of  a type of bryozoan - tiny animals which feed by waving tentacles in the water. A close-up photo of this is below. Sea mat can also colonise shells and stones.

 

 

 

 

 

These circular calcerous tubes can often be seen on seaweed - although they are very tiny, perhaps only a few millimetres long. For more information, please go to the page on worms - which is a BIG giveaway as to what they are...

 

 

Mussel byssal threads

 

This gold 'thread' is produced by mussels and is used to firmly attached the mussel to a rock or other object to prevent it floating away. So a mussel must have attached itself to this necklace shell which must have particularly galling for the necklace shell, as the mussel would have made a nice meal. Mussels have been known to use this thread production to save them from predators -wrapping them with thread which pulls them off the mussel. Perhaps this is what had happened in this case.