Slime entities use the Slimeball texture for their particles instead of the Slime texture.

Steps to Reproduce:

[Step 1] Spawn a Slime entity.
[Step 2] Notice how the Slime particles do not represent the Slime block and instead resemble the Slimeball item.

Observed Results:

Slime entity particles use the Slimeball item texture.

Expected Results:

Slime entity particles use the Slime block texture.