Are these eggs?

October 23, 2001
From: Beniamino Usai

Dear Dr Rudman
Do you know what the strange objects are that you can see on the sand in the attached photo by Guido Picchetti? The photo was taken in the south of Italy in shallow water. Those bubbles of mucus are large 3-7 centimeters and they are fixed to the sand by a strong filament. They are usually covered with sand grains. They are perhaps eggs of gasteropods?
Thank you
Best regards
Beniamino Usai

Usai, B., 2001 (Oct 23) Are these eggs?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Beniamino,
There are two possibilities. One they are the egg mass of a polychaete worm, or they are the egg mass of an opisthobranch bubble shell of the family Aglajiidae or Philinidae. The drawing on the right is of the egg masses of the philinid Philine auriformis from New Zealand [approx 20mm long]. Aglajid egg masses are usually more spherical, as in your photo. An example of an aglajid with an egg mass like in your photo would be the Indo-West Pacific species Philinopsis cyanea.

If it is a worm egg mass then the microscopic eggs will be scattered throughout the jelly. If they are the eggs of a bubble shell, then each egg will be enclosed in a thin capsule and all the capsules will be connected together by a short filament to form a string of eggs which are arranged in a spiral within the egg mass. If they grow to 7cm in length, they may be a bit large for an opisthobranch, so perhaps they are a worm egg mass.
Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Oct 23). Comment on Are these eggs? by Beniamino Usai. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

  1. Huge egg mass - Doris montereyensis ?
    From: Jackie Hildering, August 14, 2007
  2. Pleurobranchus forskalii eggs?
    From: Brian James, May 3, 2005
  3. Pink tiny nudibranch and concentric rings
    From: Francesca Riolo, March 25, 2005
  4. Galapagos egg ribbon
    From: Julianne Parolisi, January 2, 2005
  5. Nudibranch eggs on a fish
    From: Chris Grossman, August 4, 2004
  6. Unknown egg mass from Turkey
    From: Erwin Koehler , October 8, 2002
  7. Nudibranch Egg masses
    From: Laurette Hanekom, July 19, 2002
  8. Eggs
    From: Alice Lee, July 18, 2002
  9. Platydoris formosa? - egg ribbon
    From: Todd Garthwaite, June 27, 2002
  10. Do Sea Slugs lay eggs?
    From: Emily, March 13, 2002
  11. A strange place to lay eggs
    From: Mary Jane Adams , January 25, 2002
  12. Baki's Egg coils
    From: Bernard Picton, November 6, 2001
  13. Whose eggs are these?
    From: Baki Yokes, November 2, 2001
  14. number of eggs
    From: Jeanette McInnes, October 7, 2001
  15. Opisthobranch egg masses
    From: Phanor Montoya, October 7, 2000
  16. How many eggs do sea slugs lay?
    From: MIKE, October 4, 2000
  17. Eggs to identify
    From: Valda Fraser, February 21, 2000

Show factsheet and all related messages