Final answer:
The statement that some sea squirts may have a pedicle or stalk for substrate attachment is true. They use these stalks to attach to a substrate and then transform into sessile adults.
Step-by-step explanation:
Some sea squirts do have a pedicle or stalk for substrate attachment. This statement is true. Sea squirts are also known as tunicates, and they belong to the class Ascidiacea. The larval stage of tunicates is free-swimming, but upon finding a suitable substrate, they attach themselves and morph into a sessile adult. Cylindrical stalks, akin to those seen in sea squirts, are commonplace in various life forms, serving as an adhesion point or elevating structures for reproduction and dispersal.