You have the brains of a worm...
Well, not exactly… But the following press release allows us to explore a common confusion amongst ID proponents, in addition to providing more compelling evidence supporting common descent.
The origin of the brain lies in a worm: Researchers discover that the centralised nervous system of vertebrates is much older than expected
First of all, an “ancient” evolutionary prediction
The findings provide strong evidence for a theory that was first put forward by zoologist Anton Dohrn in 1875. It states that vertebrate and annelid CNS are of common descent and vertebrates have turned themselves upside down throughout the course of evolution.
So how come UcD ‘contributor’ DaveScot considers the findings an argument from incredulity? And what are ID’s explanations and or predictions?
Comparing the molecular fingerpint of Platynereis nerve cells with what is known about vertebrates revealed surprising similarities.
“Our findings were overwhelming,” says Alexandru Denes, who carried out the research in Arendt’s lab. “The molecular anatomy of the developing CNS turned out to be virtually the same in vertebrates and Platynereis. Corresponding regions give rise to neuron types with similar molecular fingerprints and these neurons also go on to form the same neural structures in annelid worm and vertebrate.”
“Such a complex arrangement could not have been invented twice throughout evolution, it must be the same system,” adds Gáspár Jékely, a researcher from Arendt’s lab, who contributed essentially to the study. “It looks like Platynereis and vertebrates have inherited the organisation of their CNS from their remote common ancestors.”
The article itself Molecular Architecture of Annelid Nerve Cord Supports Common Origin of Nervous System Centralization in Bilateria was published in Cell, Vol 129, 277-288, 20 April 2007
So let’s compare science’s approach to ID’s hypothetical approach to resolving these data.
ID: We do not know how these similarities may have arisen naturally, thus based on the improbabilities of known pathways, we conclude ‘designed’. End of story
Science:
To understand the long and rich history of science we need to go back to 1875 when Anton Dohrn made its predictions in a monograph titled “Der Ursprung der Wirbelthiere und das Princip des Functionswechsels” (The origin of vertebrates and the principle of succession of functions.)
Correspondence, Karl Ernst Von Baer (1792-1876), Anton Dohrn (1840-1909) By Groeben, Christiane, Karl Ernst “von” Baer, Anton Dohrn, Jane Marion Oppenheimer Translated by Christiane Groeben, Jane M. Oppenheimer Published 1993 DIANE p.22
Dohrn’s hypothesis about the relationship of annelids and other bilaterians was not well received initially by von Baer but it seems that over time, additional data has allowed us to delve deeper into the origin of these two body plans.
However, again, this was not an argument based on ignorance but rather an argument based on the assumption of common descent and the amount of similarities between the central nervous system of annelids
Our data indicate that this mediolateral architecture was present in the last common bilaterian ancestor and thus support a common origin of nervous system centralization in Bilateria.
Since data from fossils was unable to resolve these origins, the researchers compared a present day annelid with a present day fly.
Given the obvious paucity of information from the fossil record, the main strategy to elucidate CNS evolution is to compare nervous system development in extant forms. Our comparative study of mediolateral neural patterning and neuron-type distribution in the developing trunk CNS of the annelid Platynereis revealed an unexpected degree of similarity to the mediolateral architecture of the developing vertebrate neural tube
(See also figure 7 in the paper)
So no argument from ignorance, no argument from incredulity but an argument based on a solid foundation of science. That some ID proponents are confused about science comes to no surprise however.
PS: 
Figure 7