>>51559829Sacculina is a parasitic barnacle that burrows it's way into crabs (pic related) and attaches itself at the base of the tail pretending to be an egg-sac, modifying the crab's body chemistry and brain to make it think as if it was pregnant and protect the parasite with it's life
now this should only work on female crabs, but it forcefully castrates a male crab then floods it with female hormones to turn it physically into a female, only on genetic level could you see the crab was once male
and unlike say cordyceps it doesn't kill the crab to reproduce, it just releases it's very much crustacean looking microscopic offspring occasionally
as for how it mates? Well the thing you see here is the female sacculina, the males swim as infants into the female then degenerate into nothing but gonads
and again, this is a BARNACLE, a fellow crustacean turned into something that would make even fungi blush through sheer evolutionary adaptation
