These are cuttlefish eggs: they resemble bunches of glossy black grapes – only the eggs are not perfectly rounded but drawn out into a point. Each egg is individually strapped onto a piece of driftwood with something that looks remarkably like black sticky-tape.
The Common Cuttlefish (Sepia officinalis Linnaeus) has an elaborate mating procedure in which the male cuttlefish makes a courting display, with lots of postures, poses, and colour changes, at any likely recipient of his amorous advances. If he does not receive an identical display of movements from the other cuttlefish (which would signify he had approached another male by mistake) he assumes he is in the presence of a female.
The male cuttlefish has come prepared with a handy packet of spermatophores that he promptly delivers (using a specially adapted tentacle) through the funnel and into the body cavity of the other cuttlefish. The female then blows the fertilised eggs back out through her funnel and wraps them round objects like seaweed or driftwood. Mostly the eggs are black but they can be clear and change colour later.
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Jessica's Nature Blog 
Hello,
what did you do with the cuttlefish eggs bunches? Did you try to put them back at sea or in a seawater tank, or did you leave them dessicating on the beach?
Have a good day,
Denis
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Hello, Denis. The bunches of cuttlefish eggs were washed out to sea with the next tide. I never take live animals away from the beach. Regrettably, it is not always possible to ‘rescue’ stranded creatures. Sometimes even the most strenuous efforts to return creatures to the water are unsuccessful – either because the organisms are already too dehydrated to recover or simply because they float back to the beach on the very next tide or even the next wave.
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hello i am looking for a beach in south wales where i can find cuttlefish bone to use as moulds any ideas ? cheers dai
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Hi, Davied
I have seen lots of cuttlefish bones on both Rhossili and Whiteford Sands in Gower earlier in the year – but there didn’t seem to be much there when I visited last week. I guess they occur more or less abundantly at different times of the year depending on weather, tides, and life cycles. There would appear to be a lot of luck involved in finding larger quantities. What are you casting in the moulds? My son has done a lot of pewter and silver work using cuttle bone moulds.
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Fascinating, I have never seen them before! I’ll look out for them on my local beaches. Thanks!
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I had only seen them once before when I was a child. I wonder how rare it is to find them washed ashore like flotsam?
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Brilliant to solve the mystery of the “black Grapes” we found on Saleens Beach in Co.Waterford Ireland.
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Glad to learn that my blog helped you to solve the mystery of the cuttlefish eggs, Deirdre.
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Has anyone hatched common cuttlefish eggs we found today in Ballymoney co wexford? We found 5 small bunches washed up during our coastwatch survey today . Two were attached to velvet horn. I ll be giving those to fishermen to bring out and drop on same habitat. Three are just bunches with no attachment. We fear they will just be washed up again and would like to explore hatching.
Pleasee email me
Karin
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Hello, Karin. I am sorry that I have no idea if that is possible – but perhaps I could suggest that you contact a commercial marine aquarium or sea life centre to see if they could help.
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