Yes, I am depraved, but I was so excited to actually see this slug projecting its genitals. Amazing!
I'm fairly sure this is Cuthona fulgens, a new one for me, but there are several others that look quite similar...
Ubick et al. says says L. venusta should have triangular markings on the middle of the ventral side of the abdomen (sort of seen here) and a flat epigynum, which this seems to have. Plesiometa argyra should have longitudinal lines instead of triangles, and it only occurs in Florida, so I'm going to go with L. venusta.
Looks like a lily, not something I've encountered before, I think...
Pretty sure this is Indian Cucumber Root (Medeola virginiana).
I'm told these fellows are amphipods. What do those massive front appendages do?
No more than 1.5 cm long, observed near Orinda, CA on a dirt trail through annual grassland.