Aeolidiella alba

One of Vanjie's finds at "Car Cemetery", this small 7mm creature was moving more like a land worm or grub and not really crawling like a slug at all.

One tool I find really useful is a six inch rule (15 cm), when I find something I have never seen before, such as this specimen, I like to photograph it next to the ruler in order that I have an accurate indication of the size.