I presume the object under the crab is an egg sac, but all the examples I found on the web (admittedly all were from aquariums - I could find none from nature) were red in color. Can anyone help?
Pom Pom or Boxer Crab Egg sac
Posted 17 December 2013 - 12:40 AM
Yes, this is a parasite egg mass. The parasite infects the crab (often a barnacle parasite) and then changes the crab to a female (if it is not already) and makes the crab do its nefarious bidding - produce more parasite eggs.
The crabs are otherwise health - which of course is in the parasites interest too.