Funny looking hitch hiker (Can you ID him)

[Josh_22]

Sorry dont have a picture but I do have a discription.

I have had this rock for over a year and last night when i was looking over it I came across and little snail type thing. It has feet like a snail although its shell is formed like turtle. It is no larger then a finger nail. The funny thing is it has a small hole in the top of its shell and when I shun the light on him he sprayed some kind of clear liquid out of this hole.
What is it?????
JOSH