This video says about itself:
18 September 2014
My son was raised in the forests helping wild-craft edible mushrooms. Every year we find at least one Cauliflower – the first ending up in a bread casserole with chanterelles.
The suspect sponges that were recently found among bushes in Huizen turn out to be actually fungi. That is the conclusion of investigations by the police and the Forestry Commission.
According to the Forestry Commission in Huizen, these are innocent fungi which normally grow deep in the forest. They are harmless to dogs because the animals do not like eating the fungi. …
The past few days came from different towns alerts about baked sponges supposedly deposited by people who hate dogs.
The sponges are baked in fat and smell good for dogs and cats. But once inside the stomachs of the animals they will expand and they can be lethal.
Except in Huizen sponges were also found in Almere, Hengelo, The Hague, Leiden and Saendelft. It is still unclear whether the sponges in these other places will also prove to be cauliflower mushrooms.